GK2 and male infertility: In Gk2-7/-7 mice, the unprocessed form ofADAM3 in testicular spermatozoa and the processed form in epididymal spermatozoa were detected normally (Supplementary Fig. 2F).These results indicate that Gk2-7/-7 KO mice show male infertility due to an impairment of sperm passage through the UTJ despite proper ADAM3 processing.