Pathway
Synthesis, secretion, and deacylation of Ghrelin
Ghrelin is a peptide hormone of 28 amino acid residues which is acylated at the serine-3 of the mature peptide. Ghrelin is synthesized in several tissues: X/A-like cells of the gastric mucosa (the major source of ghrelin), hypothalamus, pituitary, adrenal gland, thyroid, breast, ovary, placenta, fallopian tube, testis, prostate, liver, gall bladder, pancreas, fat tissue, human lymphocytes, spleen, kidney, lung, skeletal muscle, myocardium, vein and skin. Ghrelin binds the GHS-R1a receptor present in hypothalamus pituitary, and other tissues. Binding causes appetite stimulation and release of growth hormone. Levels of circulating ghrelin rise during fasting, peak before a meal, and fall according to the calories ingested.
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Preproghrelin is cleaved to yield proghrelin which is then acylated by ghrelin O-acyltransferase to yield octanoyl ghrelin and decanoyl ghrelin. Only octanoyl ghrelin is able to bind and activate the GHS-R1a receptor. Unacylated ghrelin (des-acyl ghrelin) is also present in plasma but its function is controversial.
Acyl proghrelin is cleaved by prohormone convertase 1/3 to yield the mature acyl ghrelin and C-ghrelin. Secretion of ghrelin is inhibited by insulin, growth hormone (somatotropin), leptin, glucose, glucagon, and fatty acids. Secretion is stimulated by insulin-like growth factor-1 and muscarinic agonists.
In the bloodstream acyl ghrelin is deacylated by butyrylcholinesterase and platelet-activating factor acetylhydrolase. Other enzymes may also deacylate acyl ghrelin.
What the reference databases state
Statements
18 statements
18 statements · 1 reference database · Subject: Synthesis, secretion, and deacylation of Ghrelin · Sources: Reactome
- ACHE participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- BCHE participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- CRHR2 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- GCG participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- GH1 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- IGF1 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- INS participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- KLF4 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- LEP participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- MBOAT4 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- PCSK1 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- PLA2G7 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
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- SEC11A participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- SEC11C participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- SPCS1 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- SPCS2 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- SPCS3 participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only
- UCN participates in Synthesis, secretion, and deacylation of GhrelinProteinReactome R-HSA-422085Inferred only