title: The effect of N-terminal acetylation on Ca(2+)-ATPase inhibition by phospholamban.
abstract: The peptide Ac-MEKVQYLTRSAIRRASTIEMPQQAR (Ac-PLB(1-25)) representing residues 1-25 of phospholamban (PLB) inhibited the maximal activity of the Ca(2+)-ATPase of skeletal muscle sarcoplasmic reticulum by about 53%, with a Kd value of 5 microM; the equivalent non-acetylated peptide PLB(1-25) had no effect. However, it was found that the non-acetylated peptide increased the effective Kd value for inhibition by Ac-PLB(1-25) consistent with competitive binding to the ATPase, with a Kd value of 8 microM for PLB(1-25). The non-acetylated peptide must therefore be able to bind to the ATPase, but in a conformation that does not lead to inhibition of the ATPase. The identity of the N-terminal residue is important in determining the strength of binding; replacement of the Met residue by Ile led to fourfold weaker binding, again with only binding of the acetylated peptide leading to inhibition of ATPase activity.
authors.affiliation: Department of Biochemistry, University of Southampton, United Kingdom.
authors.forename: A P
authors.initials: AP
authors.lastname: Starling
authors.forename: R P
authors.initials: RP
authors.lastname: Sharma
authors.forename: J M
authors.initials: JM
authors.lastname: East
authors.forename: A G
authors.initials: AG
authors.lastname: Lee
mesh_terms: D000107:Acetylation; D000595:Amino Acid Sequence; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding; D000099211:Phospholamban
chemical_list: D002135:Calcium-Binding Proteins; D000252:Calcium-Transporting ATPases; D010446:Peptide Fragments; D000099211:Phospholamban