The EF hand is a
helix–loop–helix structural domain or ''motif'' found in a large
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
of calcium-binding
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
s.
The EF-hand motif contains a helix–loop–helix topology, much like the spread thumb and forefinger of the human hand, in which the Ca
2+ ions are coordinated by ligands within the loop. The
motif takes its name from traditional nomenclature used in describing the protein
parvalbumin
Parvalbumin (PV) is a calcium-binding protein with low molecular weight (typically 9-11 kDa). In humans, it is encoded by the ''PVALB'' gene. It is not a member of the albumin family; it is named for its size (''parv-'', from Latin ''parvus'' smal ...
, which contains three such motifs and is probably involved in
muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...
relaxation via its calcium-binding activity.
The EF-hand consists of two
alpha helices
The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues ear ...
linked by a short loop region (usually about 12
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
s) that usually binds
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...
ions. EF-hands also appear in each
structural domain of the
signaling protein
In biology, cell signaling (cell signalling in British English) or cell communication is the ability of a cell to receive, process, and transmit signals with its environment and with itself. Cell signaling is a fundamental property of all cellul ...
calmodulin
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...
and in the muscle protein
troponin-C
Troponin C is a protein which is part of the troponin complex. It contains four calcium-binding EF hands, although different isoforms may have fewer than four functional calcium-binding subdomains. It is a component of thin filaments, along wi ...
.
Calcium ion binding site
The calcium ion is coordinated in a pentagonal bipyramidal configuration. The six residues involved in the binding are in positions 1, 3, 5, 7, 9 and 12; these residues are denoted by X, Y, Z, -Y, -X and -Z. The invariant Glu or Asp at position 12 provides two oxygens for liganding calcium (bidentate ligand).
The calcium ion is bound by both
protein backbone
In organic chemistry, a peptide bond is an amide type of covalent chemical bond linking two consecutive alpha-amino acids from C1 (carbon number one) of one alpha-amino acid and N2 (nitrogen number two) of another, along a peptide or protein ch ...
atoms and by amino acid
side chain
In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called the "main chain" or backbone. The side chain is a hydrocarbon branching element of a molecule that is attached to a ...
s, specifically those of the anionic amino acid residues
aspartate
Aspartic acid (symbol Asp or D; the ionic form is known as aspartate), is an α-amino acid that is used in the biosynthesis of proteins. Like all other amino acids, it contains an amino group and a carboxylic acid. Its α-amino group is in the pro ...
and
glutamate
Glutamic acid (symbol Glu or E; the ionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can synt ...
. These residues are negatively charged and will make a charge-interaction with the positively charged calcium ion. The EF hand motif was among the first structural motifs whose sequence requirements were analyzed in detail. Five of the loop residues bind calcium and thus have a strong preference for
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
-containing side chains, especially aspartate and glutamate. The sixth residue in the loop is necessarily
glycine
Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...
due to the conformational requirements of the backbone. The remaining residues are typically
hydrophobic
In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water.
Hydrophobic molecules tend to be nonpolar and, ...
and form a
hydrophobic core that binds and stabilizes the two helices.
Upon binding to Ca
2+, this motif may undergo conformational changes that enable Ca
2+-regulated functions as seen in Ca
2+ effectors such as
calmodulin
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...
(CaM) and
troponin C
Troponin C is a protein which is part of the troponin complex. It contains four calcium-binding EF hands, although different isoforms may have fewer than four functional calcium-binding subdomains. It is a component of thin filaments, along wi ...
(TnC) and Ca
2+ buffers such as
calreticulin
Calreticulin also known as calregulin, CRP55, CaBP3, calsequestrin-like protein, and endoplasmic reticulum resident protein 60 (ERp60) is a protein that in humans is encoded by the ''CALR'' gene.
Calreticulin is a multifunctional soluble prote ...
and
calbindin D9k
Calbindins are three different calcium-binding proteins: calbindin, calretinin and S100G. They were originally described as vitamin D-dependent calcium-binding proteins in the intestine and kidney in the chick and mammals. They are now classifi ...
. While the majority of the known EF-hand calcium-binding proteins (CaBPs) contain paired EF-hand motifs, CaBPs with single EF hands have also been discovered in both bacteria and eukaryotes. In addition, "EF-hand-like motifs" have been found in a number of bacteria. Although the coordination properties remain similar with the canonical 29-residue helix–loop–helix EF-hand motif, the EF-hand-like motifs differ from EF-hands in that they contain deviations in the secondary structure of the flanking sequences and/or variation in the length of the Ca
2+-coordinating loop.
EF hands have very high selectivity for calcium. For example, the dissociation constant of alpha
parvalbumin
Parvalbumin (PV) is a calcium-binding protein with low molecular weight (typically 9-11 kDa). In humans, it is encoded by the ''PVALB'' gene. It is not a member of the albumin family; it is named for its size (''parv-'', from Latin ''parvus'' smal ...
for Ca
2+ is ~1000 times lower than that for the similar ion Mg
2+. This high selectivity is due to the relatively rigid coordination geometry, the presence of multiple charged amino acid side chains in the binding site, as well as the ion solvation properties.
Prediction
Pattern (motif signature) search is one of the most straightforward ways to predict continuous EF-hand Ca
2+-binding sites in proteins. Based on the sequence alignment results of canonical EF-hand motifs, especially the conserved side chains directly involved in Ca
2+ binding, a patter
PS50222has been generated to predict canonical EF-hand sites. Prediction servers may be found in the external links section.
Classification
Since the delineation of the EF-hand motif in 1973, the family of EF-hand proteins has expanded to include at least 66 subfamilies thus far. EF-hand motifs are divided into two major structural groups:
* Canonical EF-hands as seen in calmodulin (CaM) and the prokaryotic CaM-like protein calerythrin. The 12-residue canonical EF-hand loop binds Ca
2+ mainly via sidechain carboxylates or carbonyls (loop sequence positions 1, 3, 5, 12). The residue at the –X axis coordinates the Ca
2+ ion through a bridged water molecule. The EF-hand loop has a bidentate ligand (Glu or Asp) at axis –Z.
* Pseudo EF-hands exclusively found in the N-termini of S100 and S100-like proteins. The 14-residue pseudo EF-hand loop chelates Ca
2+ primarily via backbone carbonyls (positions 1, 4, 6, 9).
Additional points:
* EF-hand-like proteins with diversified flanking structural elements around the Ca
2+-binding loop have been reported in bacteria and viruses. These prokaryotic EF-hand-like proteins are widely implicated in Ca
2+ signaling and homeostasis in bacteria. They contain flexible lengths of Ca
2+-binding loops that differ from the EF-hand motifs. However, their coordination properties resemble classical EF-hand motifs.
** For example, the semi-continuous Ca
2+-binding site in
D-galactose-binding protein (GBP) contains a nine-residue loop. The Ca
2+ ion is coordinated by seven protein oxygen atoms, five of which are from the loop mimicking the canonical EF-loop whereas the other two are from the carboxylate group of a distant Glu.
** Another example is a novel domain named Excalibur (extracellular Ca
2+-binding region) isolated from ''
Bacillus subtilis
''Bacillus subtilis'', known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus ''Bacillus ...
''. This domain has a conserved 10-residue Ca
2+-binding loop strikingly similar to the canonical 12-residue EF-hand loop.
** The diversity of the structure of the flanking region is illustrated by the discovery of EF-hand-like domains in bacterial proteins. For example, a helix–loop–strand instead of the helix–loop–helix structure is in periplasmic galactose-binding protein (''
Salmonella typhimurium
''Salmonella enterica'' subsp. ''enterica'' is a subspecies of ''Salmonella enterica'', the rod-shaped, flagellated, aerobic, Gram-negative bacterium. Many of the pathogenic serovars of the ''S. enterica'' species are in this subspecies, includin ...
'', ) or alginate-binding protein (''
Sphingomonas sp''., ); the entering helix is missing in protective antigen (''
Bacillus anthracis
''Bacillus anthracis'' is a gram-positive and rod-shaped bacterium that causes anthrax, a deadly disease to livestock and, occasionally, to humans. It is the only permanent ( obligate) pathogen within the genus '' Bacillus''. Its infection is a ...
'', ) or dockerin (''
Clostridium thermocellum
''Acetivibrio thermocellus'' is an anaerobic, thermophilic bacterium. ''A. thermocellusm'' has garnered research interest due to its cellulolytic and ethanologenic abilities, being capable of directly converting a cellulosic substrate into eth ...
'', ).
Among all the structures reported to date, the majority of EF-hand motifs are paired either between two canonical or one pseudo and one canonical motifs. For proteins with odd numbers of EF-hands, such as the penta-EF-hand calpain, EF-hand motifs were coupled through homo- or hetero-dimerization. The recently-identified EF-hand containing ER Ca
2+ sensor protein, stromal interaction molecule 1 and 2 (STIM1, STIM2), has been shown to contain a Ca
2+-binding canonical EF-hand motif that pairs with an immediate, downstream atypical "hidden" non-Ca
2+-binding EF-hand. Single EF-hand motifs can serve as protein-docking modules: for example, the single EF hand in the NKD1 and NKD2 proteins binds the Dishevelled (DVL1, DVL2, DVL3) proteins.
Functionally, the EF-hands can be divided into two classes:
#signaling proteins
#buffering/transport proteins.
The first group is the largest and includes the most well-known members of the family such as calmodulin, troponin C and S100B. These proteins typically undergo a calcium-dependent conformational change which opens a target binding site. The latter group is represented by calbindin D9k and these proteins do not undergo calcium dependent conformational changes.
Subfamilies
* EPS15 homology (EH) domain –
Examples
Aequorin
Aequorin is a calcium binding protein (CaBP) isolated from the
cnidarian
Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter.
Their distinguishing feature is cnidocytes, specialized cells that th ...
''
Aequorea victoria
''Aequorea victoria'', also sometimes called the crystal jelly, is a bioluminescent hydrozoan jellyfish, or hydromedusa, that is found off the west coast of North America.
The species is best known as the source of two proteins involved in biolu ...
''. Aequorin belongs to the EF-hand family of CaBPs, with EF-hand loops that are closely related to CaBPs in mammals. In addition, aequorin has been used for years as an indicator of Ca
2+ and has been shown to be safe and well tolerated by cells. Aequorin is made up of two components – the calcium binding component
apoaequorin
Aequorin is a calcium-activated photoprotein isolated from the hydrozoan ''Aequorea victoria''. Its bioluminescence was studied decades before the protein was isolated from the animal by Osamu Shimomura in 1962. In the animal, the protein occur ...
(AQ) and the chemiluminescent molecule
coelenterazine
Coelenterazine is a luciferin, a molecule that emits light after reaction with oxygen, found in many aquatic organisms across eight phyla. It is the substrate of many luciferases such as '' Renilla reniformis'' luciferase (Rluc), ''Gaussia'' lucif ...
. The AQ portion of this protein contains the EF-hand calcium binding domains.
Human proteins
Humans proteins containing this domain include:
*
ACTN1;
ACTN2
Alpha-actinin-2 is a protein which in humans is encoded by the ''ACTN2'' gene. This gene encodes an alpha-actinin isoform that is expressed in both skeletal and cardiac muscles and functions to anchor myofibrillar actin thin filaments and titin t ...
;
ACTN3
Alpha-actinin-3, also known as alpha-actinin skeletal muscle isoform 3 or F-actin cross-linking protein, is a protein that in humans is encoded by the ''ACTN3'' gene (named sprinter gene, speed gene or athlete gene) located on chromosome 11. Al ...
;
ACTN4
Alpha-actinin-4 is a protein that in humans is encoded by the ''ACTN4'' gene.
Alpha actinins belong to the spectrin gene superfamily which represents a diverse group of cytoskeletal proteins, including the alpha and beta spectrins and dystrophin ...
;
APBA2BP;
AYTL1;
AYTL2
*
C14orf143;
CABP1;
CABP2;
CABP3;
CABP4;
CABP5;
CABP7;
CALB1;
CALB2;
CALM2
Calmodulin 2 is a protein that in humans is encoded by the ''CALM2'' gene.
Clinical significance
Mutations in CALM2 are associated to cardiac arrhythmias.
Interactions
CALM2 has been shown to interact with AKAP9.
See also
* calmodulin ...
;
CALM3
Calmodulin 3 is a protein that in humans is encoded by the ''CALM3'' gene.
CALM-3 is best known for contracting the heart muscles, and depending on whether this activity is consistent or not, other diseases could emerge as a downside. It is ab ...
;
CALML3;
CALML4;
CALML5;
CALML6;
CALN1;
CALU;
CAPN1
Calpain-1 catalytic subunit (CANP 1) is a protein that in humans is encoded by the ''CAPN1'' gene.
Function
The calpains, calcium-activated neutral proteases, are nonlysosomal, intracellular cysteine proteases. The mammalian calpains include ...
;
CAPN11;
CAPN2
Calpain-2 catalytic subunit is a protein that in humans is encoded by the ''CAPN2'' gene.
Function
The calpains, calcium-activated neutral proteases, are nonlysosomal, intracellular cysteine proteases. The mammalian calpains include ubiquitous ...
;
CAPN3;
CAPN9;
CAPNS1;
CAPNS2;
CAPS
Caps are flat headgear.
Caps or CAPS may also refer to:
Science and technology Computing
* CESG Assisted Products Service, provided by the U.K. Government Communications Headquarters
* Composite Application Platform Suite, by Java Caps, a Ja ...
;
CAPS2;
CAPSL;
CBARA1
Calcium-binding atopy-related autoantigen 1 is a protein that in humans is encoded by the ''CBARA1'' gene.
Clinical
Mutations in this gene have been associated with myopathy with extrapyramidal signs.Mojbafan M, Nojehdeh ST, Rahiminejad F, N ...
;
CETN1;
CETN2;
CETN3;
CHP;
CHP2;
CIB1
Calcium and integrin-binding protein 1 is a protein that in humans is encoded by the ''CIB1'' gene.
The protein encoded by this gene is a member of the calcium-binding protein family. The specific function of this protein has not yet been determ ...
;
CIB2;
CIB3;
CIB4;
CRNN
*
DGKA;
DGKB
Diacylglycerol kinase beta is an enzyme that in humans is encoded by the ''DGKB'' gene.
Function
Diacylglycerol kinases (DGKs) are regulators of the intracellular concentration of the second messenger diacylglycerol (DAG) and thus play a k ...
;
DGKG
Diacylglycerol kinase gamma is an enzyme that in humans is encoded by the ''DGKG'' gene.
This gene encodes an enzyme that is a member of the type I subfamily of diacylglycerol kinases, which are involved in lipid metabolism. These enzymes gener ...
;
DST;
DUOX1
Dual oxidase 1, also known as DUOX1 or ThOX1 (for thyroid oxidase), is an enzyme which in humans is encoded by the ''DUOX1'' gene. DUOX1 was first identified in the mammalian thyroid gland. In humans, two isoforms are found; hDUOX1 and hDUOX2 ...
;
DUOX2
Dual oxidase 2, also known as DUOX2 or ThOX2 (for thyroid oxidase), is an enzyme that in humans is encoded by the ''DUOX2'' gene. Dual oxidase is an enzyme that was first identified in the mammalian thyroid gland. In humans, two isoforms are found; ...
*
EFCAB1;
EFCAB2;
EFCAB4A;
EFCAB4B;
EFCAB6;
EFCBP1;
EFCBP2;
EFHA1;
EFHA2;
EFHB;
EFHC1;
EFHD1;
EFHD2
EF-hand domain family member D2 is a protein that in humans is encoded by the EFHD2 gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generatio ...
;
EPS15
Epidermal growth factor receptor substrate 15 is a protein that in humans is encoded by the ''EPS15'' gene.
Function
This gene encodes a protein that is part of the EGFR pathway. The protein is present at clathrin-coated pits and is involved ...
;
EPS15L1
*
FKBP10;
FKBP14;
FKBP7;
FKBP9;
FKBP9L;
FREQ;
FSTL1
Follistatin-related protein 1 is a protein that in humans is encoded by the ''FSTL1'' gene.
Structure
This gene encodes a protein with similarity to follistatin, an BMP-4-binding protein. It binds to BMP-4 and TGF-β1, but not Activin A. It c ...
;
FSTL5
*
GCA;
GPD2;
GUCA1A;
GUCA1B;
GUCA1C
*
hippocalcin;
HPCAL1;
HPCAL4;
HZGJ
*
IFPS;
ITSN1
Intersectin-1 is a protein that, in humans, is encoded by the ''ITSN1'' gene.
Function
The protein encoded by this gene is a cytoplasmic membrane-associated protein that indirectly coordinates endocytic membrane traffic with the actin assembl ...
;
ITSN2
Intersectin-2 is a protein that in humans is encoded by the ''ITSN2'' gene.
This gene encodes a cytoplasmic protein which contains SH3 domains. This protein is a member of a family of proteins involved in clathrin-mediated endocytosis. Intersect ...
;
KCNIP1
Kv channel-interacting protein 1 also known as KChIP1 is a protein that in humans is encoded by the ''KCNIP1'' gene.
Function
This gene encodes a member of the family of voltage-gated potassium ( Kv) channel-interacting proteins (KCNIPs, also ...
;
KCNIP2
Kv channel-interacting protein 2 also known as KChIP2 is a protein that in humans is encoded by the ''KCNIP2'' gene.
Function
This gene encodes a member of the family of voltage-gated potassium ( Kv) channel-interacting proteins (KCNIPs, als ...
;
KCNIP3;
KCNIP4
Kv channel-interacting protein 4 is a protein that in humans is encoded by the ''KCNIP4'' gene.
This gene encodes a member of the family of voltage-gated potassium (Kv) channel-interacting proteins (KCNIPs), which belong to the recoverin branch o ...
;
KIAA1799
*
LCP1
*
MACF1
Microtubule-actin cross-linking factor 1, isoforms 1/2/3/5 is a protein that in humans is encoded by the ''MACF1'' gene.
MACF1 encodes a large protein containing numerous spectrin and leucine-rich repeat (LRR) domains. MACF1 is a member of a fami ...
;
MRLC2;
MRLC3;
MST133;
MYL1;
MYL2;
MYL5;
MYL6B
Myosin light chain 6B is a protein that in humans is encoded by the ''MYL6B'' gene. Myosin is a hexameric ATPase cellular motor protein. It is composed of two heavy chains, two nonphosphorylatable alkali light chains, and two phosphorylatable re ...
;
MYL7
Atrial Light Chain-2 (ALC-2) also known as Myosin regulatory light chain 2, atrial isoform (MLC2a) is a protein that in humans is encoded by the ''MYL7'' gene. ALC-2 expression is restricted to cardiac muscle atria in healthy individuals, where i ...
;
MYL9
Myosin regulatory light polypeptide 9 is a protein that in humans is encoded by the ''MYL9'' gene.
Function
Myosin, a structural component of muscle, consists of two heavy chains and four light chains. The protein encoded by this gene is a my ...
;
MYLC2PL;
MYLPF
Myosin light chain, phosphorylatable, fast skeletal muscle is a protein that in humans is encoded by the MYLPF gene. It is located on chromosome 16 in humans. Myosin light chain, phosphorylatable
References
Further reading
*
*
*
*
...
*
NCALD;
NIN;
NKD1;
NKD2;
NLP;
NOX5
NADPH oxidase, EF-hand calcium binding domain 5, also known as NOX5, is a protein which in humans is encoded by the ''NOX5'' gene.
Function
NOX5 is a novel NADPH oxidase that generates superoxide
In chemistry, a superoxide is a compound ...
;
NUCB1;
NUCB2
Nucleobindin-2 is a protein that when found in humans is encoded by the ''NUCB2'' gene.
Nucleobindin-2 is a calcium-binding EF-hand protein. upplied by OMIMref name="entrez" />
NUCB2 is protein precursor of nesfatin-1
In the study of the evolu ...
*
OCM
*
PDCD6;
PEF1;
PKD2
Polycystin-2 is a protein that in humans is encoded by the ''PKD2'' gene.
This gene encodes a member of the polycystin protein family, called TRPP2, previously known as polycystin-2, PC2 or APKD2. TRPP2 contains multiple transmembrane domains, ...
;
PLCD1
1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase delta-1 is an enzyme that in humans is encoded by the ''PLCD1'' gene.
PLCd1 is essential to maintain homeostasis of the skin.
See also
Phospholipase C
Phospholipase C (PLC) is a class of ...
;
PLCD4
1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase delta-4 is an enzyme that in humans is encoded by the ''PLCD4'' gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of ...
;
PLCH1;
PLCH2 PLCH may stand for:
* Plch, a municipality in the Czech Republic
* The Public Library of Cincinnati and Hamilton County, a public library system in Cincinnati, Ohio, United States
* Pulmonary Langerhans' cell histiocytosis
Langerhans cell histioc ...
;
PLS1;
PLS3;
PP1187;
PPEF1;
PPEF2;
PPP3R1;
PPP3R2;
PRKCSH;
PVALB
Parvalbumin (PV) is a calcium-binding protein with low molecular weight (typically 9-11 kDa). In humans, it is encoded by the ''PVALB'' gene. It is not a member of the albumin family; it is named for its size (''parv-'', from Latin ''parvus'' smal ...
*
RAB11FIP3;
RASEF;
RASGRP;
RASGRP1;
RASGRP2;
RASGRP3
Ras guanyl-releasing protein 3 is a protein that in humans is encoded by the ''RASGRP3'' gene.
Function
Members of the RAS (see HRAS; MIM 190020) subfamily of GTPases function in signal transduction as GTP/GDP-regulated switches that cycle bet ...
;
RCN1;
RCN2;
RCN3;
RCV1;
RCVRN;
REPS1;
RHBDL3;
RHOT1;
RHOT2;
RPTN
Repetin is an extracellular matrix protein expressed in the epidermis. In humans it is encoded by the ''RPTN'' gene. Repetin is part of the S100 fused-type protein family and contains an EF hand structural domain.
It functions in the cornified c ...
;
RYR2
Ryanodine receptor 2 (RYR2) is one of a class of ryanodine receptors and a protein found primarily in cardiac muscle. In humans, it is encoded by the ''RYR2'' gene. In the process of cardiac calcium-induced calcium release, RYR2 is the major med ...
;
RYR3
Ryanodine receptor 3 is one of a class of ryanodine receptors and a protein that in humans is encoded by the ''RYR3'' gene. The protein encoded by this gene is both a calcium channel and a receptor for the plant alkaloid ryanodine. RYR3 and RY ...
*
S100A1
Protein S100-A1, also known as S100 calcium-binding protein A1 is a protein which in humans is encoded by the ''S100A1'' gene. S100A1 is highly expressed in cardiac and skeletal muscle, and localizes to Z-discs and sarcoplasmic reticulum. S100A1 ...
;
S100A11;
S100A12;
S100A6
S100 calcium-binding protein A6 (S100A6) is a protein that in humans is encoded by the ''S100A6'' gene.
Function
The protein encoded by this gene is a member of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 p ...
;
S100A8;
S100A9;
S100B;
S100G;
S100Z;
SCAMC-2;
SCGN;
SCN5A
Sodium channel protein type 5 subunit alpha, also known as NaV1.5 is an integral membrane protein and tetrodotoxin-resistant voltage-gated sodium channel subunit. NaV1.5 is found primarily in cardiac muscle, where it mediates the fast influx of N ...
;
SDF4;
SLC25A12
Calcium-binding mitochondrial carrier protein Aralar1 is a protein that in humans is encoded by the ''SLC25A12'' gene. Aralar is an integral membrane protein located in the inner mitochondrial membrane. Its primary function as an antiporter is the ...
;
SLC25A13
Citrin, also known as solute carrier family 25, member 13 (citrin) or SLC25A13, is a protein which in humans is encoded by the ''SLC25A13'' gene.
Citrin is associated with type II citrullinemia and neonatal intrahepatic cholestasis caused by ...
;
SLC25A23;
SLC25A24;
SLC25A25;
SPATA21;
SPTA1;
SPTAN1
Alpha II-spectrin, also known as Spectrin alpha chain, brain is a protein that in humans is encoded by the ''SPTAN1'' gene. Alpha II-spectrin is expressed in a variety of tissues, and is highly expressed in cardiac muscle at Z-disc structures, co ...
;
SRI
*
TBC1D9;
TBC1D9B;
TCHH
Trichohyalin is a protein that in mammals is encoded by the ''TCHH'' gene.
Discovery
In 1903 the name ''trichohyalin'' was assigned to the granules of the inner root sheath (IRS) of hair follicles discovered by Hans Vörner. In 1986 the name was ...
;
TESC;
TNNC1;
TNNC2
*
USP32
*
VSNL1
*
ZZEF1
See also
* Another distinct calcium-binding motif composed of alpha helices is the
dockerin domain.
References
Further reading
*
*
*
*
*
*
*
*
*
*
External links
*
*
*
*
*
*
*
{{Protein secondary structure