Effect of heparin on the expression of calmodulin-binding proteins in bull spermatozoa

J Reprod Fertil. 1989 Mar;85(2):615-22. doi: 10.1530/jrf.0.0850615.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Benzamidines / pharmacology
  • Calcium / metabolism
  • Calmodulin-Binding Proteins / metabolism*
  • Cattle / metabolism*
  • Heparin / pharmacology*
  • Male
  • Sperm Capacitation / drug effects
  • Spermatozoa / drug effects*
  • Spermatozoa / metabolism


  • Benzamidines
  • Calmodulin-Binding Proteins
  • Heparin
  • Calcium