Figure 1. The coolest image of this protein EVAH!!!

Introduction

History

In 1902, Bayliss and Starling discover a pancreatic secretin involved in regulation of water homeostasis, giving rise to interest in pancreatic hormones. Shortly after, in 1906, Moore et al. hypothesize involvement of gastrointestinal hormone extracts in maintenance of the endocrine pancreas. Jean La Barre purifies glucose-lowering gut extracts in 1929 and characterizes them as incretins, which stands for intestine secretion insulin. Finally, in 1984, gastric inhibitory peptide (or, GIP) is isolated from porcupine intestine. Although GIP was initially found to have gastric inhibitory effects, it was also shown that the polypeptide initiated insulin secretion. Interestingly, the effect of GIP on insulin levels was still seen in its absence, signaling the presence of an additional incretin, which has now been classified as glucagon-like peptide-1 (GLP-1).

General Structure

Subunit Architecture

Glucose-dependent Insulinotropic Polypeptide

Active Site

Figure 2. Crucial interaction between Tyr1 of GIP and corresponding GIPR residues.

Associated Diseases

Medical Relevance

Tirzepatide