PMID: 23689510

Authors:

Ravn P, Madhurantakam C, Kunze S, Matthews E, Priest C, O'brien S, Collinson A, Papworth M, Fritsch-Fredin M, Jermutus L, Benthem L, Gruetter M, Jackson RH

Title:

Structural and Pharmacological Characterisation of Novel Potent and Selective Monoclonal Antibody Antagonists of Glucose-Dependent Insulinotropic Polypeptide Receptor.

Journal:

J Biol Chem. 2013 May 20.

Abstract:

Glucose-dependent insulinotropic polypeptide (GIP) is an endogenous hormonal factor (incretin) that upon binding to its receptor (GIPr; a class B GPCR), stimulates insulin secretion by beta cells in the pancreas, There has been a lack of potent inhibitors of the GIPr with prolonged in vivo exposure, to investigate GIP biology. Here we describe here the generation of an antagonizing antibody to the GIPr, using phage and ribosome display libraries. Gipg013 is a specific competitive antagonist with equally high potencies to mouse, rat, dog and human GIP receptors with a Ki of 7 nM for the human GIPr. Gipg013 antagonises the GIP receptor and inhibits GIP induced insulin secretion in vivo. A crystal structure of Gipg013 Fab in complex with the human GIPr ECD indicates that the antibody binds through a series of hydrogen bonds from the CDRs of Gipg013 Fab to the N-terminal alpha-helix of GIPr extracellular domain (ECD) as well as to residues around its highly conserved glucagon receptor sub-family recognition fold. The antibody epitope overlaps with the GIP binding site on GIPr ECD ensuring competitive antagonism of the receptor. This well characterized antagonizing antibody to the GIPr will be useful as a tool to further understand the biological roles of GIP.