WHAT HAVE SNAKES TAUGHT US ABOUT INTEGRINS

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