Understanding protein‐protein interaction network: a case study with glutaminase interacting protein

Abstract

Glutaminase interacting protein (GIP) is a 124 amino acid long protein containing single PDZ domain. This protein intersects a number of important biological pathways, of which many are unknown. Its involvement in cancer pathways makes it a good target for drug design based on the structure. We resolved the solution structures of both free GIP and GIP in complex with C‐terminal peptide analog of glutaminase L to shed light on the mechanism of binding with the goal of future development of a potential inhibitor for GIP. To understand more of GIP's function, interactions with two target peptides were investigated using different biophysical methods. One of the peptide had the C‐terminus of brain‐specific angiogenesis inhibitor 2 (BAI2) and the other one used had a consensus PDZ class I binding motif. Both of the peptides showed moderate binding affinity toward GIP with BAI2 peptide having comparatively higher affinity. Elucidating the mechanism of interactions for different target partners would help to lay out the network of function for GIP. This research was financially supported by USDA PECASE Presidential Early Career Award for Scientists and Engineers award 2003–35302‐12930, NSF Grant IBN‐0628064, USDA Grant 2011–65503‐20030 and NIH Grant DK082397 to Smita Mohanty.