title: Mastoparan binds to glycogen phosphorylase to regulate sarcoplasmic reticular Ca2+ release in skeletal muscle.
abstract: The ryanodine receptor, a Ca(2+)-releasing channel in sarcoplasmic reticulum (SR), plays an important role in the excitation-contraction coupling of skeletal muscle. In a previous study [Hirata, Nakahata and Ohizumi (2000) Mol. Pharmacol. 57, 1235-1242], we reported that mastoparan caused Ca(2+) release through ryanodine receptor from the heavy fraction of SR (HSR) isolated from rabbit skeletal muscle, and that it specifically bound to a 97 kDa protein which was distinct from Ca(2+)-pump or triadin. The present study was undertaken to identify and characterize the 97 kDa mastoparan-binding protein. The 97 kDa protein was purified from solubilized HSR by DEAE-Sepharose column chromatography and preparative SDS/PAGE. The partial amino acid sequence of the purified 97 kDa protein was matched with that of glycogen phosphorylase (GP). The proteolytic cleavage pattern of the 97 kDa protein was identical with that of GP. Furthermore, [(125)I-Tyr(3)]mastoparan specifically bound to GP. Interestingly, mastoparan-induced Ca(2+) release was inhibited by exogenous addition of GP-a, and mastoparan dissociated GP from HSR. These results indicate that the 97 kDa mastoparan-binding protein is GP, which negatively regulates Ca(2+) release from HSR. There may be a functional cross-talk between Ca(2+) release from HSR and glycogenolysis for energy supply mediated through GP in skeletal muscles.
authors.affiliation: Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-Ku, Sendai 980-8578, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hirata
authors.forename: Masanori
authors.initials: M
authors.lastname: Atsumi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ohizumi
authors.forename: Norimichi
authors.initials: N
authors.lastname: Nakahata
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002847:Chromatography, Agarose; D004591:Electrophoresis, Polyacrylamide Gel; D024981:Glycogen Phosphorylase / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins; D007457:Iodine Radioisotopes / Q000378:metabolism; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides; D011485:Protein Binding / Q000187:drug effects; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism; D014862:Wasp Venoms / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D007457:Iodine Radioisotopes; D010455:Peptides; D014862:Wasp Venoms; C037500:mastoparan; D024981:Glycogen Phosphorylase; D002118:Calcium