Secretin family receptor proteins, also known as Family B or family 2 of G-protein coupled receptors are regulated by

peptide hormones Peptide hormones or protein hormones are hormones whose molecules are peptide, or proteins, respectively. The latter have longer amino acid chain lengths than the former. These hormones have an effect on the endocrine system of animals, including h ...

from the

glucagon hormone family Glucagon/gastric inhibitory polypeptide/secretin/vasoactive intestinal peptide hormones are a family of evolutionarily related peptide hormones that regulate activity of G-protein-coupled receptors from the secretin receptor family. A number of ...

. The family is different from

adhesion G protein-coupled receptors Adhesion G protein-coupled receptors (adhesion GPCRs) are a class of 33 human protein receptors with a broad distribution in embryonic and larval cells, cells of the reproductive tract, neurons, leukocytes, and a variety of tumours. Adhesion GPC ...

. The secretin-receptor family of GPCRs include

vasoactive intestinal peptide receptor There are two known receptors for the vasoactive intestinal peptide (VIP) termed VPAC1 and VPAC2. These receptors bind both VIP and pituitary adenylate cyclase-activating polypeptide (PACAP) to some degree. Both receptors are members of the 7 tra ...

s and receptors for

secretin Secretin is a hormone that regulates water homeostasis throughout the body and influences the environment of the duodenum by regulating secretions in the stomach, pancreas, and liver. It is a peptide hormone produced in the S cells of the du ...

calcitonin Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates. in the ultimopharyngeal body. It acts to reduce blood calcium (Ca2+), opposing the ...

and

parathyroid hormone Parathyroid hormone (PTH), also called parathormone or parathyrin, is a peptide hormone secreted by the parathyroid glands that regulates the serum calcium concentration through its effects on bone, kidney, and intestine. PTH influences bone ...

/parathyroid hormone-related peptides. These receptors activate

adenylyl cyclase Adenylate cyclase (EC 4.6.1.1, also commonly known as adenyl cyclase and adenylyl cyclase, abbreviated AC) is an enzyme with systematic name ATP diphosphate-lyase (cyclizing; 3′,5′-cyclic-AMP-forming). It catalyzes the following reaction: :A ...

and the phosphatidyl-inositol-calcium pathway. The receptors in this family have 7

transmembrane A transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequent ...

helices,; ; like rhodopsin-like GPCRs. However, there is no significant sequence identity between these two GPCR families and the secretin-receptor family has its own characteristic 7TM signature. The secretin-receptor family GPCRs exist in many animal species. Data mining with the

Pfam Pfam is a database of protein families that includes their annotations and multiple sequence alignments generated using hidden Markov models. The most recent version, Pfam 35.0, was released in November 2021 and contains 19,632 families. Uses ...

signature has identified members in fungi, although due to their presumed non-hormonal function they are more commonly referred to as

Adhesion G protein-coupled receptor Adhesion G protein-coupled receptors (adhesion GPCRs) are a class of 33 human protein receptors with a broad distribution in embryonic and larval cells, cells of the reproductive tract, neurons, leukocytes, and a variety of tumours. Adhesion GPC ...

s, making the ''Adhesion'' subfamily the more basal group. Three distinct sub-families (B1-B3) are recognized.

Subfamily B1

Subfamily B1 contains classical

hormone receptor A hormone receptor is a receptor molecule that binds to a specific chemical messenger . Hormone receptors are a wide family of proteins made up of receptors for thyroid and steroid hormones, retinoids and Vitamin D, and a variety of other recepto ...

s, such as receptors for

and

glucagon Glucagon is a peptide hormone, produced by alpha cells of the pancreas. It raises concentration of glucose and fatty acids in the bloodstream, and is considered to be the main catabolic hormone of the body. It is also used as a medication to tre ...

, that are all involved in cAMP-mediated signalling pathways. * Pituitary adenylate cyclase-activating polypeptide type 1 receptor ** PACAPR (ADCYAP1R1) * Calcitonin receptor ** CALCR *

Corticotropin-releasing hormone receptor Corticotropin-releasing hormone receptors (CRHRs), also known as corticotropin-releasing factor receptors (CRFRs) are a G protein-coupled receptor family that binds corticotropin-releasing hormone (CRH). There are two receptors in the family, ...

** CRHR1; CRHR2 * Glucose-dependent insulinotropic polypeptide receptor/Gastric inhibitory polypeptide receptor ** GIPR * Glucagon receptor ** GCGR * Glucagon receptor-related ** GLP1R; GLP2R; * Growth hormone releasing hormone receptor **

GHRHR The growth-hormone-releasing hormone receptor (GHRHR) is a G-protein-coupled receptor that binds growth hormone-releasing hormone. The GHRHR activates a Gs protein that causes a cascade of cAMP via adenylate cyclase. Function This gene, exp ...

* Parathyroid hormone receptor ** PTHR1; PTHR2 * Secretin receptor ** SCTR *

Vasoactive intestinal peptide receptor There are two known receptors for the vasoactive intestinal peptide (VIP) termed VPAC1 and VPAC2. These receptors bind both VIP and pituitary adenylate cyclase-activating polypeptide (PACAP) to some degree. Both receptors are members of the 7 tra ...

VIPR1 Vasoactive intestinal polypeptide receptor 1 also known as VPAC1, is a protein, that in humans is encoded by the ''VIPR1'' gene. VPAC1 is expressed in the brain (cerebral cortex, hippocampus, amygdala), lung, prostate, peripheral blood leuko ...

;

VIPR2 Vasoactive intestinal peptide receptor 2 also known as VPAC2, is a G-protein coupled receptor that in humans is encoded by the ''VIPR2'' gene. Tissue distribution VIPR2 is expressed in the uterus, prostate, smooth muscle of the gastroin ...

Subfamily B2

Subfamily B2 contains receptors with long extracellular N-termini, such as the leukocyte cell-surface antigen CD97; calcium-independent receptors for latrotoxin and brain-specific angiogenesis inhibitor receptors amongst others. They are otherwise known as

s. * Brain-specific angiogenesis inhibitor ** BAI1;

BAI2 BAI or Bai may refer to: BAI Organizations *BAI Communications, telecommunications infrastructure company * BAI (organization), professional organization for financial services in the United States * Badminton Association of India, India's go ...

; BAI3 * CD97 antigen ** CD97 * EMR hormone receptor ** CELSR1;

CELSR2 Cadherin EGF LAG seven-pass G-type receptor 2 is a protein that in humans is encoded by the ''CELSR2'' gene. The protein encoded by this gene is a member of the flamingo subfamily, part of the cadherin superfamily. The flamingo subfamily consi ...

; CELSR3;

EMR1 EGF-like module-containing mucin-like hormone receptor-like 1 also known as F4/80 is a protein encoded by the ''ADGRE1'' gene. EMR1 is a member of the adhesion GPCR family. Adhesion GPCRs are characterized by an extended extracellular region o ...

; EMR2; EMR3; EMR4 * GPR56 orphan receptor ** GPR56; GPR64; GPR97; GPR110; GPR111; GPR112; GPR113; GPR114;

GPR115 Probable G-protein coupled receptor 115 is a protein that in humans is encoded by the ''GPR115'' gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ' ...

; GPR123; GPR125; GPR126; GPR128; GPR133;

GPR144 Probable G-protein coupled receptor 144 is a protein that in humans is encoded by the ''GPR144'' gene. This gene encodes a member of the adhesion-GPCR family of receptors. Family members are characterised by an extended extracellular region wit ...

; GPR157 * Latrophilin receptor **

ELTD1 EGF, latrophilin and seven transmembrane domain-containing protein 1 is a latrophilin-like orphan receptor of the adhesion G protein-coupled receptor family. In humans this protein is encoded by the ''ELTD1'' gene. ELTD1 appears to have a role i ...

;

LPHN1 Latrophilin 1 is a protein that in humans is encoded by the ''ADGRL1'' gene. It is a member of the adhesion-GPCR family of receptors. Family members are characterized by an extended extracellular region with a variable number of protein domains ...

;

LPHN2 Latrophilin 2 is a protein that in humans is encoded by the ''ADGRL2'' gene. This gene encodes a member of the latrophilin subfamily of G-protein coupled receptors (GPCR). Latrophilins may function in both cell adhesion and signal transduction. I ...

;

LPHN3 Latrophilin 3 is a protein that in humans is encoded by the ''ADGRL3'' gene. Function This gene encodes a member of the latrophilin subfamily of G protein-coupled receptors (GPCR). Latrophilins may function in both cell adhesion and signal tr ...

* Ig-hepta receptor ** GPR116

Subfamily B3

Subfamily B3 includes

Methuselah Methuselah () ( he, מְתוּשֶׁלַח ''Məṯūšélaḥ'', in pausa ''Məṯūšālaḥ'', "His death shall send" or "Man of the javelin" or "Death of Sword"; gr, Μαθουσάλας ''Mathousalas'') was a biblical patriarch and a f ...

and other

Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many speci ...

proteins. Other than the typical seven-transmembrane region, characteristic structural features include an amino-terminal extracellular domain involved in ligand binding, and an intracellular loop (IC3) required for specific G-protein coupling. * Diuretic hormone receptor

Unclassified members

HCTR-5; HCTR-6; KPG 006; KPG 008

References

{{G protein-coupled receptors Protein domains Protein families G protein-coupled receptors