The adhesive and signaling functions of integrins are regulated through their cytoplasmic domains. We identified a novel 111 residue polypeptide, designated beta 3-endonexin, that interacted with the cytoplasmic tail of the beta 3 integrin subunit in a yeast two-hybrid system. This interaction is structurally specific, since it was reduced by 64% by a point mutation in the beta 3 cytoplasmic tail (S752-->P) that disrupts integrin signaling. Moreover, this interaction is integrin subunit specific since it was not observed with the cytoplasmic tails of the alpha IIb, beta 1, or beta 2 subunits. beta 3-Endonexin fusion proteins bound selectively to detergent-solubilized beta 3 from platelets and human umbilical vein endothelial cells, and beta 3-endonexin mRNA and protein were detected in platelets and other tissues. A related mRNA encoded a larger polypeptide that failed to bind to beta integrin tails. The apparent specificity of beta 3-endonexin for the beta 3 integrin subunit suggests potential mechanisms for selective modulation of integrin functions.
Beta 3-endonexin, a novel polypeptide that interacts specifically with the cytoplasmic tail of the integrin beta 3 subunit.
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S J Shattil, T O'Toole, M Eigenthaler, V Thon, M Williams, B M Babior, M H Ginsberg; Beta 3-endonexin, a novel polypeptide that interacts specifically with the cytoplasmic tail of the integrin beta 3 subunit.. J Cell Biol 1 November 1995; 131 (3): 807–816. doi: https://doi.org/10.1083/jcb.131.3.807
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