The Role of Hydrophobic Amino Acids in the Structure and Function of the Rhodopsin Family of G Protein-Coupled Receptors

Recent advances in crystallization methods have permitted to resolve the molecular structure of several members of the rhodopsin family of G protein-coupled receptors (GPCRs). Comparison among these structures revealed a number of conserved polar and charged residues implicated in the receptor transduction pathways. These residues function as micro-switches in the process of receptor activation and has been the object of study of many research groups. However, hydrophobic forces, usually underappreciated, also play a major role in GPCR function. Conserved hydrophobic residues contribute significantly to receptor activation, G protein coupling, and oligomerization processes. This review focuses on the impact of the hydrophobic amino acids observed in the structure of class A GPCRs necessary for their function. This information represents a fundamental piece to complete a holistic view of the GPCR signal transduction machinery.