Structural elucidation of integrin alphaIIbbeta3 cytoplasmic domain by nuclear magnetic resonance spectroscopy

Integrin alphaIIbbeta3 is a heterodimeric (alpha/beta) cell surface receptor critical for platelet aggregation, and its dysfunction is linked to thrombosis and a number of other vascular diseases. Upon agonist stimulation, which leads to platelet aggregation, alphaIIbbeta3 is activated via a distinct inside-out signaling pathway, i.e., the short alphaIIb/beta3 cytoplasmic tails receive intracellular signals, which trigger the conformational change of the extracellular domain for the high-affinity ligand binding. The structural basis for how the alphaIIbbeta3 cytoplasmic face regulates the inside-out activation of the receptor has been extensively studied over the past decade. We have recently used nuclear magnetic resonance (NMR) spectroscopy to characterize and determine the structural features of the alphaIIbbeta3 cytoplasmic domain. This chapter describes detailed practical procedures for performing these NMR studies, which have provided key atomic insights into the mechanism of the alphaIIbbeta3 function, especially its inside-out signaling.