Glucose-dependent insulinotropic polypeptide: difference between revisions
Diff·revision 6 → 7·11:21, 5 Jul 2024
Difference between revision 6 and revision 7 of Glucose-dependent insulinotropic polypeptide. 5 lines changed; the page grew by 793 bytes.
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| 10 | GIP is processed post-translationally from pro-GIP and circulates in two forms: the active GIP (1–42) and an N-terminally cleaved GIP (3–42) produced by dipeptidyl peptidase-4 cleavage. Both forms retain insulin-secretory activity, which is unusual among incretin peptides and is the basis for the ''glucose-dependent'' descriptor — GIP potentiates insulin secretion only when glucose is elevated.{{r|deacon1995}} | 10 | GIP is processed post-translationally from pro-GIP and circulates in two forms: the active GIP (1–42) and an N-terminally cleaved GIP (3–42) produced by dipeptidyl peptidase-4 cleavage. Both forms retain insulin-secretory activity, which is unusual among incretin peptides and is the basis for the ''glucose-dependent'' descriptor — GIP potentiates insulin secretion only when glucose is elevated.{{r|deacon1995}} |
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| + | 12 | == Biosynthesis and secretion == | |
| + | 13 | GIP is encoded by the ''GIP'' gene and is processed from a 153-residue pro-GIP. Like GLP-1, it is subject to tissue-specific post-translational modification. In K cells, endopeptidases cleave pro-GIP to release the active hormone. The principal stimuli are glucose and long-chain fatty acids; amino acids are a weaker stimulus.{{r|nauck2019}} | |
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| + | 15 | K cells are found predominantly in the duodenum and jejunum, extending into the ileum in smaller numbers. They are open-type epithelial cells with an apical surface exposed to the lumen, allowing direct contact with nutrient-induced secretagogues. Secretion is biphasic: an early phase within 15 minutes of ingestion, followed by a later more sustained phase as nutrients pass through the intestine.{{r|nauck2019}} | |
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| 12 | == References == | 17 | == References == |
| 13 | {{reflist}} | 18 | {{reflist}} |