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 duodenum, which are located in the intestinal glands. In humans, the secretin peptide is encoded by the SCT gene.
Peptide hormones are hormones whose molecules are peptides. Peptide hormones have shorter amino acid chain lengths than protein hormones. These hormones have an effect on the endocrine system of animals, including humans. Most hormones can be classified as either amino-acid-based hormones or steroid hormones. The former are water-soluble and act on the surface of target cells via second messengers; the latter, being lipid-soluble, move through the plasma membranes of target cells to act within their nuclei.
Glucagon is a peptide hormone, produced by alpha cells of the pancreas. It raises the 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 treat a number of health conditions. Its effect is opposite to that of insulin, which lowers extracellular glucose. It is produced from proglucagon, encoded by the GCG gene.
Gastrin is a peptide hormone that stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum, and the pancreas.
Gastric inhibitory polypeptide(GIP), also known as glucose-dependent insulinotropic polypeptide, is an inhibiting hormone of the secretin family of hormones. While it is a weak inhibitor of gastric acid secretion, its main role, being an incretin, is to stimulate insulin secretion.
Amylin, or islet amyloid polypeptide (IAPP), is a 37-residue peptide hormone. It is co-secreted with insulin from the pancreatic β-cells in the ratio of approximately 100:1 (insulin:amylin). Amylin plays a role in glycemic regulation by slowing gastric emptying and promoting satiety, thereby preventing post-prandial spikes in blood glucose levels.
Enteroglucagon is a peptide hormone derived from preproglucagon. It is a gastrointestinal hormone, secreted from mucosal cells primarily of the colon and terminal ileum. It consists of 37 amino acids. Enteroglucagon is released when fats and glucose are present in the small intestine; which decrease the motility to allow sufficient time for these nutrients to be absorbed.
Proprotein convertase 1, also known as prohormone convertase, prohormone convertase 3, or neuroendocrine convertase 1 and often abbreviated as PC1/3 is an enzyme that in humans is encoded by the PCSK1 gene. PCSK1 and PCSK2 differentially cleave proopiomelanocortin and they act together to process proinsulin and proglucagon in pancreatic islets.
Pancreatic polypeptide (PP) is a polypeptide secreted by PP cells in the endocrine pancreas. It regulates pancreatic secretion activities, and also impacts liver glycogen storage and gastrointestinal secretion. Its secretion may be impacted by certain endocrine tumours.
Glucagon-like peptide-1 (GLP-1) is a 30- or 31-amino-acid-long peptide hormone deriving from the tissue-specific posttranslational processing of the proglucagon peptide. It is produced and secreted by intestinal enteroendocrine L-cells and certain neurons within the nucleus of the solitary tract in the brainstem upon food consumption. The initial product GLP-1 (1–37) is susceptible to amidation and proteolytic cleavage, which gives rise to the two truncated and equipotent biologically active forms, GLP-1 (7–36) amide and GLP-1 (7–37). Active GLP-1 protein secondary structure includes two α-helices from amino acid position 13–20 and 24–35 separated by a linker region.
Pancreatic elastase is a form of elastase that is produced in the acinar cells of the pancreas, initially produced as an inactive zymogen and later activated in the duodenum by trypsin. Elastases form a subfamily of serine proteases, characterized by a distinctive structure consisting of two beta barrel domains converging at the active site that hydrolyze amides and esters amongst many proteins in addition to elastin, a type of connective tissue that holds organs together. Pancreatic elastase 1 is a serine endopeptidase, a specific type of protease that has the amino acid serine at its active site. Although the recommended name is pancreatic elastase, it can also be referred to as elastase-1, pancreatopeptidase, PE, or serine elastase.
Peptide YY (PYY), also known as peptide tyrosine tyrosine, is a peptide that in humans is encoded by the PYY gene. Peptide YY is a short peptide released from cells in the ileum and colon in response to feeding. In the blood, gut, and other elements of periphery, PYY acts to reduce appetite; similarly, when injected directly into the central nervous system, PYY is also anorexigenic, i.e., it reduces appetite.
The glucagon receptor is a 62 kDa protein that is activated by glucagon and is a member of the class B G-protein coupled family of receptors, coupled to G alpha i, Gs and to a lesser extent G alpha q. Stimulation of the receptor results in the activation of adenylate cyclase and phospholipase C and in increased levels of the secondary messengers intracellular cAMP and calcium. In humans, the glucagon receptor is encoded by the GCGR gene.
The glucagon-like peptide-1 receptor (GLP1R) is a G protein-coupled receptor (GPCR) found on beta cells of the pancreas and on neurons of the brain. It is involved in the control of blood sugar level by enhancing insulin secretion. In humans it is synthesised by the gene GLP1R, which is present on chromosome 6. It is a member of the glucagon receptor family of GPCRs. GLP1R is composed of two domains, one extracellular (ECD) that binds the C-terminal helix of GLP-1, and one transmembrane (TMD) domain that binds the N-terminal region of GLP-1. In the TMD domain there is a fulcrum of polar residues that regulates the biased signaling of the receptor while the transmembrane helical boundaries and extracellular surface are a trigger for biased agonism.
The gastric inhibitory polypeptide receptor (GIP-R), also known as the glucose-dependent insulinotropic polypeptide receptor, is a protein that in humans is encoded by the GIPR gene.
Carboxypeptidase E (CPE), also known as carboxypeptidase H (CPH) and enkephalin convertase, is an enzyme that in humans is encoded by the CPE gene. This enzyme catalyzes the release of C-terminal arginine or lysine residues from polypeptides.
Glucagon-like peptide-2 receptor (GLP-2R) is a protein that in human is encoded by the GLP2R gene located on chromosome 17.
Pancreatic Stone Protein (PSP), also known as Lithostathine-1-alphaislet cells regeneration factor (ICRF) or islet of Langerhans regenerating protein (REG) is a protein that in humans is encoded by the REG1A gene as a single polypeptide of 144 amino acids further cleaved by trypsin to produce a 133 amino acid protein that is O-linked glycosylated on threonine 27. This protein is a type I subclass member of the Regenerating protein family. The Reg protein family is a multi protein family grouped into four subclasses, types I, II, III and IV based on the primary structures of the proteins. Reg family members REG1B, REGL, PAP and this gene are tandemly clustered on chromosome 2p12 and may have arisen from the same ancestral gene by gene duplication. The PSP is mostly produced in Human by the acinar cells of the pancreas and is secreted in the duodenum by the same pathway that pancreatic exocrine enzymes. It has C-terminal C-type lectin domain whose binding partner is currently unknown.
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.
Ribonuclease 4 is an enzyme that in humans is encoded by the RNASE4 gene.
