Perinuclear membrane localization of alphaKAP, a protein produced from a gene within the gene of calmodulin-dependent protein kinase IIalpha.
AlphaKAP is a protein produced from a gene within the gene of the a isoform of calmodulin-dependent protein kinase II (CaM-kinase IIa). It consists of the association domain of CaM-kinase IIa and a highly hydrophobic amino-terminal stretch consisting of 25 amino acids which is absent from CaM-kinase IIalpha. We previously demonstrated that alphaKAP is an integral membrane protein by subcellular fractionation analysis [Sugai, R., Takeuchi, M., Okuno, S., and Fujisawa, H. (1996) J. Biochem. 120, 773-779], but the exact subcellular localization of alphaKAP was not well understood. Here we demonstrate that alphaKAP is localized on the nuclear membrane of COS-7 cells transiently expressing alphaKAP. The nuclear membrane and perinuclear small vesicles were immunostained with an antibody against a synthetic peptide corresponding to the carboxyl-terminal 15 amino acids of alphaKAP. In contrast to the intact alphaKAP, the mutant alphaKAP, from which the hydrophobic amino-terminal segment had been deleted, accumulated within nuclei. Thus, alphaKAP may function as an anchoring protein for CaM-kinase II and/or other proteins in the perinuclear membrane.
Takeuchi
M
M
Department of Biochemistry, Asahikawa Medical College, Hokkaido.
Fujisawa
H
H
D000818:Animals; D019556:COS Cells / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D009685:Nuclear Envelope / Q000201:enzymology / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology / Q000378:metabolism
D007527:Isoenzymes; D008565:Membrane Proteins; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases