Recovery of penetration ability in protease-treated zona-free mouse eggs occurs coincident with recovery of a cell surface 94 kD protein.
Previous studies have demonstrated that protease treatment of zona-free mouse eggs impairs sperm-egg interaction (Boldt et al.: Biol Reprod 39:19-27, 1988) and causes modification of a 94 kD egg plasma membrane protein (Boldt et al., Gamete Res 23:91-101, 1989). In this report, the ability of eggs to recover penetration ability following protease treatment was examined. Zona-free mouse eggs were isolated and treated with either trypsin or chymotrypsin (1 mg/ml, 20 min), then cultured for 0, 3, or 6 hr before insemination. Eggs cultured for 3 or 6 hr displayed significantly higher penetration levels than eggs inseminated immediately after protease treatment, indicating a recovery of penetration ability during the 3 or 6 hr incubation period. The recovery of penetration ability was not blocked by inclusion of cyclohexamide (50 micrograms/ml) during the 3 or 6 hr culture period, indicating that protein synthesis was not required for recovery of fusion ability. Cell surface radiolabeling studies with 125I revealed that a 94 kD cell surface protein was lost immediately following trypsin or chymotrypsin treatment but was found on the egg surface after the 3 or 6 hr recovery period. Recovery of the 94 kD egg surface protein occurred in the presence of cyclohexamide, and metabolic radiolabeling studies with 35S-methionine confirmed that synthesis of a 94 kD protein was blocked by cyclohexamide. These results suggest that the recovery of penetration ability after protease treatment of zona-free eggs is due to recovery of the 94 kD cell surface protein, providing further evidence for the involvement of the 94 kD protein in sperm-egg interaction.
Kellom
T
T
Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta.
Vick
A
A
Boldt
J
J
D000818:Animals; D010450:Endopeptidases / Q000494:pharmacology; D005260:Female; D008297:Male; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D009865:Oocytes / Q000502:physiology*; D013084:Sperm-Ovum Interactions / Q000187:drug effects / Q000502:physiology*
D008565:Membrane Proteins; D010450:Endopeptidases