Cloning and Characterization of a Homologous Ca²⁺/Calmodulin-Dependent Protein Kinase PSKH1 from Pearl Oyster Pinctada fucata

Many of the effects of Ca²⁺ signaling are mediated through the Ca²⁺/calmodulin complex and its acceptors, the Ca²⁺/calmodulin-dependent protein kinases, including PSKH1. Studies of the proteins involved in the calcium metabolism in oysters will help elucidate the pearl formation mechanism. This paper describes a full-length PSKH1 cDNA isolated from pearl oyster Pinctada fucata. Oyster PSKH1 shares 65% homology with human PSKH1 and 48% similarity with rat CaM kinase I in the amino acid sequence, and contains a calmodulin-binding domain. The results of semi-quantitative reverse transcription-polymerase chain reaction and in situ hybridization revealed that oyster PSKH1 mRNA is highly expressed in the outer epithelial cells of the mantle pallial and in the gill epithelial cells. These studies provide important information describing the complex Ca²⁺ signaling mechanism in oyster calcium metabolism.