Structural Elucidation of Integrin IIb3 Cytoplasmic Domain by Nuclear Magnetic Resonance Spectroscopy

Integrin α_IIb β₃ is a heterodimeric (α/β) 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, α_IIb β₃ is activated via a distinct inside-out signaling pathway, i.e., the short α_IIb /β₃ 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 α_IIb β₃ 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 α_IIb β₃ cytoplasmic domain. This chapter describes detailed practical procedures for performing these NMR studies, which have provided key atomic insights into the mechanism of the α_IIb β₃ function, especially its inside-out signaling.