The disintegrin-like domain of the snake venom metalloprotease alternagin inhibits alpha 2 beta 1 integrin-mediated cell adhesion

The alpha (2)beta (1) integrin is a major collagen receptor that plays an e ssential role in the adhesion of normal and tumor cells to the extracellula r matrix. Here we describe the isolation of a novel metalloproteinase/disin tegrin, which is a potent inhibitor of the collagen binding to alpha (2)bet a (1) integrin. This 55-kDa protein (alternagin) and its disintegrin domain (alternagin-C) were isolated from Bothrops alternatus snake venom. Amino a cid sequencing of alternagin-C revealed the disintegrin structure. Alternag in and alternagin-C inhibit collagen I-mediated adhesion of K562-alpha (2)b eta (1)-transfected cells, The IC50 was 134 and 100 nM for alternagin and a lternagin-C, respectively. Neither protein interfered with the adhesion of cells expressing alpha (IIb)beta (3), alpha (1)beta (1), alpha (5)beta (1), alpha (4)beta (1) alpha (v)beta (3), and alpha (9)beta (1) integrins to ot her ligands such as fibrinogen, fibronectin, and collagen IV. Alternagin an d alternagin-C also mediated the adhesion of the K562-alpha (2)beta (1)-tra nsfected cells. Our results show that the disintegrin-like domain of altern agin is responsible for its ability to inhibit collagen binding to alpha (2 )beta (1) integrin. (C) 2000 Academic Press.