title: Immunological detection of phospholamban phosphorylation states facilitates the description of the mechanism of phosphorylation and dephosphorylation.
abstract: Six electrophoretically distinct species of oligomeric phospholamban were identified immunologically following phosphorylation of sarcoplasmic reticulum vesicles by cAMP-dependent protein kinase. The phosphate content of each was determined, confirming that the discrete sequential retardation of phospholamban oligomers was the result of ascending mole ratios of phosphate (P0-P5) per oligomer. These data afford support to the pentameric arrangement of oligomeric phospholamban and offer a means of determining phosphorylation stoichiometry independent of the absolute phospholamban concentration. Detection of the relative concentration of individual species during phosphorylation facilitated the description of a random mechanism of phosphorylation by cAMP-dependent protein kinase. By contrast, dephosphorylation of cAMP-dependent protein kinase phosphorylated phospholamban was shown to exhibit strong positive cooperativity in its reaction mechanism.
authors.affiliation: Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
authors.forename: C F
authors.initials: CF
authors.lastname: Li
authors.forename: J H
authors.initials: JH
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Colyer
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D002135:Calcium-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D002417:Cattle; D004285:Dogs; D007120:Immunochemistry; D066298:In Vitro Techniques; D007700:Kinetics; D010766:Phosphorylation; D011487:Protein Conformation; D011494:Protein Kinases / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D000099211:Phospholamban
chemical_list: D000255:Adenosine Triphosphate; D002135:Calcium-Binding Proteins; D011494:Protein Kinases; D000099211:Phospholamban; C022571:adenosine 5'-O-(3-thiotriphosphate)