The disintegrin-like domain of the snake venom metalloprotease alternagin inhibits α2β1 integrin-mediated cell adhesion

The alpha (2)beta (1) integrin is a major collagen receptor that plays an essential role in the adhesion of normal and tumor cells to the extracellular matrix. Here we describe the isolation of a novel metalloproteinase/disintegrin, which is a potent inhibitor of the collagen binding to alpha (2)beta (1) integrin. This 55-kDa protein (alternagin) and its disintegrin domain (alternagin-C) were isolated from Bothrops alternatus snake venom. Amino acid sequencing of alternagin-C revealed the disintegrin structure. Alternagin and alternagin-C inhibit collagen I-mediated adhesion of K562-alpha (2)beta (1)-transfected cells, The IC50 was 134 and 100 nM for alternagin and alternagin-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 other ligands such as fibrinogen, fibronectin, and collagen IV. Alternagin and alternagin-C also mediated the adhesion of the K562-alpha (2)beta (1)-transfected cells. Our results show that the disintegrin-like domain of alternagin is responsible for its ability to inhibit collagen binding to alpha (2)beta (1) integrin. (C) 2000 Academic Press.