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Phospholamban
Phospholamban, also known as PLN or PLB, is a micropeptide protein that in humans is encoded by the ''PLN'' gene. Phospholamban is a 52-amino acid integral membrane protein that regulates the calcium (Ca2+) pump in cardiac muscle cells. Function This protein is found as a pentamer and is a major substrate for the cAMP-dependent protein kinase (PKA) in cardiac muscle. In the unphosphorylated state, phospholamban is an inhibitor of cardiac muscle sarcoplasmic reticulum Ca2+-ATPase ( SERCA2) which transports calcium from cytosol into the sarcoplasmic reticulum. When phosphorylated (by PKA) - disinhibition of Ca2+-ATPase of SR leads to faster Ca2+ uptake into the sarcoplasmic reticulum, thereby contributing to the lusitropic response elicited in heart by beta-agonists. The protein is a key regulator of cardiac diastolic function. Mutations in this gene are a cause of inherited human dilated cardiomyopathy with refractory congestive heart failure. When phospholamban is phosp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
ATP2A1
Sarcoplasmic/endoplasmic reticulum calcium ATPase 1 (SERCA1) also known as Calcium pump 1, is an enzyme that in humans is encoded by the ''ATP2A1'' gene. Function This gene encodes one of the SERCA Ca2+-ATPases, which are intracellular pumps located in the sarcoplasmic or endoplasmic reticula of muscle cells. This enzyme catalyzes the hydrolysis of ATP coupled with the translocation of calcium from the cytosol to the sarcoplasmic reticulum lumen, and is involved in muscular excitation and contraction. Clinical significance Mutations in this gene cause some autosomal recessive forms of Brody disease, characterized by increasing impairment of muscular relaxation during exercise. Alternative splicing results in two transcript variants encoding different isoforms. Alternative splicing of ATP2A1 is also implicated in myotonic dystrophy type 1. ATP2A1 SERCA pumps were very strongly down regulated in amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS), al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Sarcolipin
Sarcolipin is a micropeptide protein that in humans is encoded by the ''SLN'' gene. Function Sarcoplasmic reticulum Ca2+-ATPases are transmembrane proteins that catalyze the ATP-dependent transport of Ca2+ from the cytosol into the lumen of the sarcoplasmic reticulum in muscle cells. The SLN gene encodes a small transmembrane proteolipid that regulates several sarcoplasmic reticulum Ca2+-ATPases by reducing the accumulation of Ca2+ in the sarcoplasmic reticulum without affecting the rate of ATP hydrolysis. Ablation of sarcolipin increases atrial Ca2+ transient amplitudes and enhanced atrial contractility. Furthermore, atria from sarcolipin- null mice have blunted response to isoproterenol stimulation, implicating sarcolipin as a mediator of beta-adrenergic responses in atria. Sarcolipin is an important mediator of muscle based non shivering thermogenesis (NST). It causes the sarcoplasmic reticulum Ca2+-ATPases to stop pumping Ca2+ ions but continue futilely hydrolysing ATP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Sarcoplasmic Reticulum
The sarcoplasmic reticulum (SR) is a membrane-bound structure found within muscle cells that is similar to the smooth endoplasmic reticulum in other cells. The main function of the SR is to store calcium ions (Ca2+). Calcium ion levels are kept relatively constant, with the concentration of calcium ions within a cell being 10,000 times smaller than the concentration of calcium ions outside the cell. This means that small increases in calcium ions within the cell are easily detected and can bring about important cellular changes (the calcium is said to be a second messenger). Calcium is used to make calcium carbonate (found in chalk) and calcium phosphate, two compounds that the body uses to make teeth and bones. This means that too much calcium within the cells can lead to hardening (calcification) of certain intracellular structures, including the mitochondria, leading to cell death. Therefore, it is vital that calcium ion levels are controlled tightly, and can be released int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Protein Kinase A
In cell biology, protein kinase A (PKA) is a family of serine-threonine kinases whose activity is dependent on cellular levels of cyclic AMP (cAMP). PKA is also known as cAMP-dependent protein kinase (). PKA has several functions in the cell, including regulation of glycogen, sugar, and lipid metabolism. It should not be confused with 5'-AMP-activated protein kinase (AMP-activated protein kinase). History Protein kinase A, more precisely known as adenosine 3',5'-monophosphate (cyclic AMP)-dependent protein kinase, abbreviated to PKA, was discovered by chemists Edmond H. Fischer and Edwin G. Krebs in 1968. They won the Nobel Prize in Physiology or Medicine in 1992 for their work on phosphorylation and dephosphorylation and how it relates to PKA activity. PKA is one of the most widely researched Protein kinase, protein kinases, in part because of its uniqueness; out of 540 different protein kinase genes that make up the human kinome, only one other protein kinase, casein kinase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Micropeptide
Micropeptides (also referred to as microproteins) are polypeptides with a length of less than 100-150 amino acids that are encoded by short open reading frames (sORFs). In this respect, they differ from many other active small polypeptides, which are produced through the posttranslational Proteolysis, cleavage of larger polypeptides. In terms of size, micropeptides are considerably shorter than "canonical" proteins, which have an average length of 330 and 449 amino acids in prokaryotes and eukaryotes, respectively. Micropeptides are sometimes named according to their genomic location. For example, the translated product of an upstream open reading frame (uORF) might be called a uORF-encoded peptide (uPEP). Micropeptides lack an N-terminal signaling sequences, suggesting that they are likely to be localized to the cytoplasm. However, some micropeptides have been found in other cell compartments, as indicated by the existence of Transmembrane domain, transmembrane micropeptides. They ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Lusitropic
Lusitropy or lucitropy is the rate of myocardial relaxation. The increase in cytosolic calcium of cardiomyocytes via increased uptake leads to increased myocardial contractility (positive inotropic effect), but the myocardial relaxation, or lusitropy, decreases. This should not be confused, however, with catecholamine-induced calcium uptake into the sarcoplasmic reticulum, which increases lusitropy. __TOC__ Positive lusitropy Increased catecholamine levels promote positive lusitropy, enabling the heart to relax more rapidly. This effect is mediated by the phosphorylation of phospholamban and troponin I via a cAMP-dependent pathway. Catecholamine-induced calcium influx into the sarcoplasmic reticulum increases both inotropy and lusitropy. In other words, a quicker reduction in cytosolic calcium levels (because the calcium enters the sarcoplasmic reticulum) causes an increased rate of relaxation (a positive lusitropy), however, this also enables a greater degree of calcium efflux, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
