A 27-kDa matrix receptor from rat brain synaptosomes: selective recognition of the Arg-Gly-Asp-Ser domain and unique resistance to calcium-dependent proteolysis.

A 27-kDa protein from adult rat brain synaptosomes was purified by matrix-affinity chromatography. The matrix receptor interacted with the Arg-Gly-Asp-Ser sequence recognized by integrin-type adhesion molecules, and was labeled by integrin antibodies. Levels of the 27-kDa species in brain membranes were unaffected by proteolysis, however, conventional integrin subunits exhibited robust degradation. This unique resistance to proteolysis may allow the new matrix receptor to contribute to the stability of synaptic contacts.