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Echinobase
ECB-ART-36681
Biochem J 1997 Jul 15;325 ( Pt 2):411-6. doi: 10.1042/bj3250411.
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Activation of sea-urchin sperm motility is accompanied by an increase in the creatine kinase exchange flux.

Dorsten FA , Wyss M , Wallimann T , Nicolay K .


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The kinetics of the creatine kinase (CK) reaction were studied in suspensions of quiescent and active, intact sea-urchin spermatozoa in artificial seawater, using 31P-NMR magnetization transfer. In inactive sperm, no CK-mediated exchange flux was detected, whereas in activated motile sperm, the forward pseudo-first-order rate constant was 0.13+/-0.04 s-1 at 10 degrees C, corresponding to a steady-state CK flux of 3.1+/-0.5 mM.s-1. Intracellular pH shifted from 6.6+/-0.1 to 7.6+/-0.1 upon activation. The phosphocreatine (PCr)/ATP and PCr/Pi ratios were only marginally reduced in activated sperm, whereas the estimated cytosolic free ADP concentration increased remarkably from 9 microM in quiescent, to 114 microM in activated spermatozoa. The elevation of CK flux upon sperm activation is discussed in the light of the proposition that in sea-urchin spermatozoa, which are fuelled entirely by oxidative phosphorylation, high-energy phosphate transport is mediated by a ''CK/PCr shuttle''.

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Genes referenced: LOC100887844 LOC593358

References [+] :
Bessman, The creatine-creatine phosphate energy shuttle. 1985, Pubmed