The nature of an iso-antigen of the human sperm membrane

An iso-antigen has been isolated from tritium-labelled human spermatozoa by detergent solubilization, lectin affinity chromatography and indirect immunoprecipitation using human iso-antisera. Isolated material was characterized by SDS-polyacrylamide gel electrophoresis. With these iso-antisera it was possible to isolate material showing the same electrophoresis pattern, i.e. four polypeptide chains, one of molecular weight 41000, two around 77000 and one about 120000. The same pattern was obtained with an auto-antiserum. Sequential indirect immunoprecipitation showed that iso- and auto-antisera can react against the same antigen.