Effect of heparin on the expression of calmodulin-binding proteins in bull spermatozoa.
A 125I-labelled calmodulin gel overlay procedure in the presence and the absence of Ca2+ was used to evaluate bull spermatozoa calmodulin-binding proteins. Frozen spermatozoa were thawed, washed and incubated for 6 h before being processed for SDS polyacrylamide gel electrophoresis and the 125I-labelled calmodulin gel overlay procedure. In non-incubated spermatozoa, up to 14 binding proteins were detected. Some exhibited greater calmodulin binding in the presence of Ca2+ while others exhibited greater binding when Ca2+ was absent. When heparin (2 micrograms/ml) was present in the incubation medium, a decrease in the calmodulin binding to the proteins of Mr 28,000 and 30,000 was detected in the presence of Ca2+ and EGTA. This effect of heparin was time- and dose-dependent and was increased by the presence of the acrosin inhibitor benzamidine. Sperm capacitation could thus be related to a decrease in the binding of calmodulin to these proteins.
Leclerc
P
P
Centre de Recherche du CHUL, Sante-Foy, Québec, Canada.
Langlais
J
J
Lambert
R D
RD
Sirard
M A
MA
Chafouleas
J G
JG
D000818:Animals; D001550:Benzamidines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002417:Cattle / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology*; D008297:Male; D013075:Sperm Capacitation / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects* / Q000378:metabolism
D001550:Benzamidines; D002148:Calmodulin-Binding Proteins; D006493:Heparin; D002118:Calcium