I Domain Integrins

Madamanchi A, Santoro SA, Zutter MM, Aasakiran Madamanchi, Samuel A. Santoro, Mary M. Zutter, Madamanchi, Aasakiran, Santoro, Samuel A., Zutter, Mary M.

The α2β1 integrin, also known as VLA-2, GPIa-IIa, CD49b, was first identified as an extracellular matrix receptor for collagens and/or laminins [55, 56]. It is now recognized that the α2β1 integrin serves as a receptor for many matrix and nonmatrix molecules [35, 79, 128]. Extensive analyses have clearly elucidated the α2 I domain structural motifs required for ligand binding, and also defined distinct conformations that lead to inactive, partially active or highly active ligand binding [3, 37, 66, 123, 136, 137, 140]. The mechanisms by which the α2β1 integrin plays a critical role in platelet function and homeostasis have been carefully defined via in vitro and in vivo experiments [76, 104, 117, 125]. Genetic and epidemiologic studies have confirmed human physiology and disease states mediated by this receptor in immunity, cancer, and development [6, 20, 21, 32, 43, 90]. The role of the α2β1 integrin in these multiple complex biologic processes will be discussed in the chapter.