Specificity of antibodies to the novel proteins. (A) Testicular germ cells were isolated from testis, boiled in 3% SDS with 5% β-mercaptoethanol, subjected to SDS-PAGE and blotted with antibodies. Two antibodies were used for the test of antibody specificity to each protein. The first one is a control antibody affinity-purified against GST (G) protein from each serum. The second one is a test antibody affinity-purified against each GST fusion protein (G-F) used for immunization and serum production. ADAM2, known to exhibit spermatogenic cell-specific expression, was included as a control. (B) GST or GST fusion (GST-F) proteins were added to a buffer containing the first antibodies during the incubation of immune blot analysis.