Effect of calmodulin antagonists on calcium pump of ram spermatozoa plasma membrane

H. Breitbart, S. Rubinstein

Research output: Contribution to journalArticlepeer-review

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Plasma membranes isolated from ram spermatozoa contain calmodulin, which represents approximately 0.03% of the total sperm calmodulin and 0.025% of the membrane protein. When membranes were isolated in the presence of ethylene glycol (βaminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA), the amount of calmodulin associated with the plasma membranes was reduced by only 20% The ATP-dependent calcium transport activity of the isolated plasma membranes is not enhanced by adding calmodulin and not inhibited by the calmodulin antagonists trifluoperazine (TFP), compound 48/80, or calmidazolium. In fact, there is an enhancement of calcium uptake by the calmodulin antagonists and this enhancement can be blocked by the Ca2 +-channel blocker D-600. It is suggested that the ATP-dependent calcium transport activity in the plasma membrane of ram spermatozoa is not regulated by calmodulin.

Original languageEnglish
Pages (from-to)229-235
Number of pages7
JournalSystems Biology in Reproductive Medicine
Issue number3
StatePublished - 1988


  • Calcium pump
  • Calmodulin
  • Plasma membrane


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