Glucose-dependent insulinotropic polypeptide

Gastric inhibitory polypeptide
Identifiers
Symbol	GIP
Entrez	2695
HUGO	4270
OMIM	137240
RefSeq	NM_004123
UniProt	P09681
Other data
Locus	Chr. 17 q21.3-q22

Gastric inhibitory polypeptide (GIP), also known as the glucose-dependent insulinotropic peptide, is an inhibiting hormone of the secretin family of hormones.

GIP, along with glucagon-like peptide-1 (GLP-1), belongs to a class of molecules referred to as incretins.

GIP is derived from a 153-amino acid proprotein encoded by the GIP gene and circulates as a biologically active 42-amino acid peptide. It is synthesized by K cells, which are found in the mucosa of the duodenum and the jejunum of the gastrointestinal tract.

Like all endocrine hormones, it is transported by blood.

Gastric inhibitory polypeptide receptors are seven-transmembrane proteins found on beta-cells in the pancreas.

It has traditionally been named gastrointestinal inhibitory peptide or gastric inhibitory peptide and was found to decrease the secretion of stomach acid to protect the small intestine from acid damage, reduce the rate at which food is transferred through the stomach, and inhibit the GI motility and secretion of acid. However, this is incorrect, as it was discovered that these effects are achieved only with higher-than-normal physiological level, and that these results naturally occur in the body through a similar hormone, secretin.

It is now believed that the function of GIP is to induce insulin secretion, which is stimulated primarily by hyperosmolarity of glucose in the duodenum. After this discovery, some researchers prefer the new name of glucose-dependent insulinotropic peptide, while retaining the acronym "GIP." The amount of insulin secreted is greater when glucose is administered orally than intravenously.

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