Identification of novel interaction partners for the conserved membrane proximal region of alpha-integrin cytoplasmic domains

The alpha 3A beta 1 integrin is a laminin receptor with a broad specificity for different laminin isoforms. Furthermore, it regulates the function of other integrins, like alpha 2 beta 1, alpha 5 beta 1 and alpha 6A beta 1. I n a yeast two hybrid screen of a human placenta cDNA library, we identified cDNAs coding for four different proteins that strongly interact with the c onserved region of the cytoplasmic domain of the alpha 3A integrin subunit. In addition to the cDNA for nucleotide exchange factor Mss4 and the putati ve tumour suppressor protein BIN1, two novel cDNAs mere identified. Associa tion analysis with different integrin subunits revealed them as cDNAs that encode binding proteins which react with a broad spectrum of a subunits. Th e conserved membrane proximal region of the alpha 3A chain was identified a s the binding site for all four proteins. They, therefore, may be involved in the regulation of general functions of integrins. (C) 1999 Federation of European Biochemical Societies.