The Role of Common Carp (Cyprinus carpio) Muscle Creatine Kinase Isoenzymes at Temperature Acclimation

Abstract

Creatine kinase plays a key role in the energy metabolism of cells that have fluctuating energy requirements. In vertebrates, the creatine kinase isoenzyme family consists two cytosolic and two mitochondrial forms. Only one M-CK isoform was known until we identified another three carp M-CK isoenzymes. Herein, we examine the effect of temperature changes on the temporal and spatial expressions of these three M-CK isoenzymes. Enzyme-linked immunosorbent assay experimental results indicate that these three M-CK isoforms are expressed at each temperature examined. Consistent with this result, immuno- histochemical staining also showed that these M-CK isoenzymes are co-localized in the same cellular compartment. In addition, the formation of both homo- and heterogeneous complexes among M 1-, M 2, and M3-CK was darified by coimmunoprecipitation and in vitro transcription and translation coupled GST-pull-down assay. We also generated M-CK homo- and heterodimer models to demonstrate the interactions of these monomers. Therefore, we propose that M-CK homo- or heterodimer formation undergoes an exchange according to acclimation to mircoenvironmental temperatures and relative pH values. We think that this MM-CK homo- and heterodimer exchange plays an important role as a temporal energy buffer with a spatial buffering function.