Protein–glycolipid interactions during spermatogenesis. Binding of specific germ cell proteins to sulfatoxygalactosylacylalkylglycerol, the major glycolipid of mammalian male germ cells

Abstract

Specific binding of membrane proteins extracted from rat spermatogenic cells to the major glycolipid of the male germ cell has been demonstrated by affinity chromatography. A new method for the production of affinity matrices, using photoactivatable heterobifunctional cross-linking agents, has been used to immobilize sulfatoxygalactosylacylalkylglycerol. Three proteins of apparent molecular weights 68 000, 34 000, and 24 000 from spermatogenic cells have been shown to selectively and reversibly bind to this affinity matrix. Antiserum raised against the major of these species (68 000) was demonstrated to be specific for this protein by immunoblotting. A new technique for the reduction of background nonspecific antibody staining using this method is described. The immune serum has been used to localize the antigen in frozen testicular sections. The protein is present in the plasma membranes of all germ cells, but the expression is elevated for testicular spermatozoa and cells in or near the basal compartment of the seminiferous epithelium. The relevance of these findings to intercellular communication and spermatogenesis is discussed.