Structure and function of G proteins

Abstract

G proteins are heterotrimeric proteins involved in the transduction of a variety of external signals in all eukaryotic organisms. This review analyzes the molecular aspects of G protein structure and function. The cloning of cDNAs coding for a great variety of G protein subunits has allowed us to deduce the primary and secondary structure of the subunits. Emphasis is given to the dissection of the molecular regions of the G alpha subunits implicated in the binding and hydrolysis of GTP and in the interaction with the receptor, with the effector and with the beta gamma dimer. The localization of these regions in a two-dimensional model of the G alpha subunit is attempted to provide a more comprehensive view of the structure and function of G proteins.