Light-induced Interaction of Putative Phosducin with Gβγ-subunits of G-protein in the Ciliate Blepharisma japonicum

Immunoblot of whole-cell lysate from Blepharisma japonicum with a polyclonal antibody raised against the rat phosducin display one major protein band of molecular weight of 28 kDa. Immunoprecipitation of detected phosducin immunoanalogue from lysateof dark-and light-adapted ciliates with the anti-phosducin antibody and subsequent analysis of the precipitated protein with a monoclonalantibody raised against phosphoserine residues revealed also the presence of a 28 kDa protein phosphorylated on a serine residues. Thisphosphoprotein exists in a highly phosphorylated form in ciliates adapted to darkness and its dephosphorylation occurs in illuminated cells. An immunoblot assay of the precipitated phosducin-related protein with a rabbit polyclonal antibody directed against β-subunit of G-proteinshowed one major protein band of molecular weight of about 34 kDa in lysate obtained from ciliates exposed to light. In addition, basedon partial cloning of the putative ciliate phosducin nucleotide sequence homology to the phosducin belonging to the subgroup Ⅰ of phosducinprotein family was deduced. The results obtained in this study confirm the previously reported hypothesis that in the ciliated protest Blepharisma japonicum phosducin does exist and resembles that observed in a wide variety of higher eukaryotes and also in some microorganisms.

並列關鍵字

Blepharisma japonicum ； ciliate ； G-protein ； phosducin ； protein phosphorylation ； photophobic response ； photosensory transduction

國際替代計量

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