A testicular protein important for fertility has glutathione S-transferase activity and is localized extracellularly in the seminiferous tubules.
A 24-kDa protein isolated by preparative gel electrophoresis from rat testes was reported by us as an active immunogen in rats. Anti-24-kDa antibodies inhibited murine sperm-oocyte binding in vitro. Here, we show similarity at the NH2 terminus shared by this protein purified on Sephadex G-75 followed by anion exchange high performance liquid chromatography with glutathione S-transferase (GST)-mu subunits. This protein purified by glutathione affinity chromatography also demonstrated similarity to GST-mu NH2 terminus in a 30-amino-acid overlap. Both proteins showed activity toward the GST substrate 1-chloro-2,4-dinitrobenzene (Km of 33 microM and 50 microM) which was inhibited by 17 beta-estradiol 3-sulfate. Antisera against both proteins recognized liver GST-mu on Western blots and sperm acrosome of multiple species immunocytochemically. Both antisera significantly inhibited in vitro fertilization of goat oocytes by sperm preincubated with them while anti-liver GST sera did not. GST activity was localized on rat sperm, seminiferous tubular fluid, and Sertoli cells. Seminiferous tubular fluid 24-kDa protein shared similarity to the NH2 terminus of GST-mu subunits in a 20-amino-acid overlap. Time-dependent accumulation of GST was detected in the spent culture medium of seminiferous tubules from rats of different ages suggesting secretion.
Aravinda
S
S
National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India.
Gopalakrishnan
B
B
Dey
C S
CS
Totey
S M
SM
Pawshe
C H
CH
Salunke
D
D
Kaur
K
K
Shaha
C
C
D000595:Amino Acid Sequence; D000818:Animals; D005260:Female; D005298:Fertility; D005982:Glutathione Transferase / Q000032:analysis* / Q000302:isolation & purification / Q000502:physiology; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D051381:Rats; D017208:Rats, Wistar; D012671:Seminiferous Tubules / Q000201:enzymology*; D012708:Sertoli Cells / Q000201:enzymology; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000201:enzymology
D005982:Glutathione Transferase