Phospholamban regulation of cardiac sarcoplasmic reticulum (Ca(2+)-Mg2+)-ATPase. Mechanism of regulation and site of monoclonal antibody interaction.
Monoclonal antibodies raised against canine cardiac sarcoplasmic reticulum phospholamban were used to study the structure-function relationship between phospholamban and the sarcoplasmic reticulum (SR) (Ca(2+)-Mg2+)-ATPase (Suzuki, T., and Wang, J. H. (1986) J. Biol. Chem. 261, 7018-7023). Additional monoclonal antibodies are characterized further. When five of these monoclonal antibodies were assessed for their ability to affect SR Ca2+ uptake three of these antibodies had no effect on SR Ca2+ uptake, whereas the other two monoclonals were able to stimulate SR Ca2+ uptake to levels similar to those caused by phosphorylation of phospholamban at different calcium concentrations. Using synthetic peptides corresponding to various portions of phospholamban in a competitive binding assay, it was possible to map the epitope site of monoclonals which stimulate the (Ca(2+)-Mg2+)-ATPase activity to phospholamban residues 7-16. These results implicate phospholamban residues 7-16 in the regulation of the (Ca(2+)-Mg2+)-ATPase.
Morris
G L
GL
Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
Cheng
H C
HC
Colyer
J
J
Wang
J H
JH
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism*; D001666:Binding Sites, Antibody; D017301:Ca(2+) Mg(2+)-ATPase / Q000276:immunology / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000276:immunology / Q000378:metabolism*; D004285:Dogs; D000939:Epitopes / Q000032:analysis; D007700:Kinetics; D008969:Molecular Sequence Data; D009206:Myocardium / Q000201:enzymology*; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides / Q000138:chemical synthesis / Q000494:pharmacology; D011487:Protein Conformation; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D000099211:Phospholamban
D000911:Antibodies, Monoclonal; D017301:Ca(2+) Mg(2+)-ATPase; D002135:Calcium-Binding Proteins; D000252:Calcium-Transporting ATPases; D000939:Epitopes; D010446:Peptide Fragments; D010455:Peptides; D000099211:Phospholamban