Identification of mobile and fixed antigens on the plasma membrane of rat spermatozoa using monoclonal antibodies.
We have used monoclonal antibodies to study the mobility and distribution of three different antigens on the cell surface of rat spermatozoa. We classified two of the antigens (designated 2B1 and 2D6) as 'mobile', since when detected by indirect immunofluorescence they were situated over the entire sperm flagellum and were susceptible to antibody-induced patching. Patching was critically dependent upon antibody concentrations and was much reduced at 4 degrees C. Patching of the 2B1 antigen was not induced by the 2B1 monoclonal antibody alone. Thus, 2B1 antibody labelled directly with fluorescein bound with a uniform distribution over the sperm flagellum, but this uniform fluorescence was made patchy on subsequent incubation in an unlabelled second antibody layer of anti-mouse IgG anti-serum. By 'Western blotting', the 2B1 antigen was found to be located to a 40 kD molecular weight polypeptide. The remaining 'fixed' antigen (designated 1B6) was not susceptible to antibody-induced patching, and was restricted to a discrete domain on the post-acrosomal region of the sperm surface. We discuss the relationship between mobility of sperm surface antigens and their segregation to discrete domains on the plasma membrane.
D000818:Animals; D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000032:analysis*; D002462:Cell Membrane / Q000276:immunology; D005455:Fluorescent Antibody Technique; D007152:Immunologic Capping; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013082:Sperm Tail / Q000276:immunology; D013091:Spermatogenesis; D013094:Spermatozoa / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface