Functional plasticity of the BNIP-2 and Cdc42GAP Homology (BCH) domain in cell signaling and cell dynamics

The BNIP-2 and Cdc42GAP Homology (BCH) domains constitute a new and expanding family of highly conserved scaffold protein domains that regulate Rho, Ras and MAPK signaling, leading to cell growth, apoptosis, morphogenesis, migration and differentiation. Such versatility is achieved via their ability to target small GTPases and their immediate regulators such as GTPase-activating proteins (GAPs) and guanine nucleotide exchange factors (GEFs), their ability to form intra-molecular or inter-molecular interaction with itself or with other BCH domains, and also by their ability to bind diverse cellular proteins such as membrane receptors, isomerase, caspases and metabolic enzymes such as glutaminase. The presence of BCH and BCH-like domains in various proteins and their divergence from the ancestral lipid-binding CRAL-TRIO domain warrant the need to examine closely their structural, functional and regulatory plasticity in isolation or in concert with other protein modules present in the same proteins.