What have snakes taught us about integrins?

Snake venoms contain unique components that affect cell-matrix interactions. Disintegrins represent a class of low molecular weight, Arg-Gly-Asp (RGD)containing, cysteine-rich peptides purified from the venom of various snakes among the Viperidae and Crotalidae. They bind with various degrees of specificity to integrins alpha(IIb)beta(3), alpha(5)beta(1) and alpha(V)beta(3) expressed on cells. Snake venom metalloproteases thigh molecular mass haemorrhagins) also contain disintegrin-like domains, in addition to zinc-chelating sequences. Membrane-anchored ADAMs (A Disintegrin And Metalloprotease domain), multidomain molecules consisting of metalloprotease, disintegrin-like, cysteine-rich, and epidermal growth factor domains, a transmembrane domain and a cytoplasmic tail, are a new family of proteins. In the light of the large number and wide distribution of ADAMs, they may participate in cell-cell fusion events, including sperm-egg binding and fusion, myoblast fusion and other cell-cell and cell-matrix interactions. The structure-function relationship of these molecules is discussed.