title: cDNA cloning and characterization of a novel calmodulin-like protein from pearl oyster Pinctada fucata.
abstract: Calcium metabolism in oysters is a very complicated and highly controlled physiological and biochemical process. However, the regulation of calcium metabolism in oyster is poorly understood. Our previous study showed that calmodulin (CaM) seemed to play a regulatory role in the process of oyster calcium metabolism. In this study, a full-length cDNA encoding a novel calmodulin-like protein (CaLP) with a long C-terminal sequence was identified from pearl oyster Pinctada fucata, expressed in Escherichia coli and characterized in vitro. The oyster CaLP mRNA was expressed in all tissues tested, with the highest levels in the mantle that is a key organ involved in calcium secretion. In situ hybridization analysis reveals that CaLP mRNA is expressed strongly in the outer and inner epithelial cells of the inner fold, the outer epithelial cells of the middle fold, and the dorsal region of the mantle. The oyster CaLP protein, with four putative Ca(2+)-binding domains, is highly heat-stable and has a potentially high affinity for calcium. CaLP also displays typical Ca(2+)-dependent electrophoretic shift, Ca(2+)-binding activity and significant Ca(2+)-induced conformational changes. Ca(2+)-dependent affinity chromatography analysis demonstrated that oyster CaLP was able to interact with some different target proteins from those of oyster CaM in the mantle and the gill. In summary, our results have demonstrated that the oyster CaLP is a novel member of the CaM superfamily, and suggest that the oyster CaLP protein might play a different role from CaM in the regulation of oyster calcium metabolism.
authors.affiliation: Institute of Marine Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Li
authors.forename: Liping
authors.initials: L
authors.lastname: Xie
authors.forename: Zhuojun
authors.initials: Z
authors.lastname: Ma
authors.forename: Rongqing
authors.initials: R
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002147:Calmodulin / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D002942:Circular Dichroism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D020869:Gene Expression Profiling; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010125:Ostreidae / Q000033:anatomy & histology / Q000737:chemistry / Q000235:genetics*; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013050:Spectrometry, Fluorescence; D014020:Tissue Extracts
chemical_list: D002147:Calmodulin; D018076:DNA, Complementary; D012333:RNA, Messenger; D014020:Tissue Extracts; D002118:Calcium