Biophysical and Biochemical Methods to Study GPCR Oligomerization

Abstract

Traditionally, G protein-coupled receptors (GPCRs) were believed to exist and function as single monomeric entities that interacted with only G proteins to produce an intracellular signal. However, intensive research in the field now clearly indicates that receptors exist in a multiprotein complex, interacting with other GPCRs and intracellular regulatory proteins to form homo- or hetero-oligomeric signaling units (reviewed in refs. 1–5). The existence of direct receptor-receptor interactions adds an additional level of complexity to the regulation of GPCR function in cells co-expressing various GPCRs. Furthermore, the discovery that GPCRs can interact to form hetero-oligomeric complexes, often with novel pharmacological and functional properties, has shed much light on the previously unexplained behavior of many agonists in vivo and on the mechanisms by which different pathways and receptor systems can intersect and crossreact to produce an integrated signal and cellular response.