title: Stoichiometry of lipid-protein interaction assessed by hydrophobic photolabeling.
abstract: Here we undertook a comparative study of the composition of the lipid annulus of three ATPases pertaining to the P-type family: plasma membrane calcium pump (PMCA), sarcoplasmic reticulum calcium pump (SERCA) and Na,K-ATPase. The photoactivatable phosphatidylcholine analogue [(125)I]TID-PC/16 was incorporated into mixtures of dimyristoyl phosphatidylcholine (DMPC) and each enzyme with the aid of the nonionic detergent C(12)E(10). After photolysis, the extent of the labeling reaction was assessed to determine the lipid:protein stoichiometry: 17 for PMCA, 18 for SERCA, 24 for the Na,K-ATPase (alpha-subunit) and 5.6 mol PC/mol protein for the Na,K-ATPase (beta-subunit).
authors.affiliation: Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956.C1113AAD, Buenos Aires, Argentina.
authors.forename: Ana María
authors.initials: AM
authors.lastname: Villamil Giraldo
authors.forename: Pablo Raúl
authors.initials: PR
authors.lastname: Castello
authors.forename: F Luis
authors.initials: FL
authors.lastname: González Flecha
authors.forename: Jesper V
authors.initials: JV
authors.lastname: Moeller
authors.forename: José María
authors.initials: JM
authors.lastname: Delfino
authors.forename: Juan Pablo F C
authors.initials: JP
authors.lastname: Rossi
mesh_terms: D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000378:metabolism*; D003902:Detergents / Q000737:chemistry; D006801:Humans; D008027:Light; D008055:Lipids / Q000737:chemistry*; D015394:Molecular Structure; D010713:Phosphatidylcholines / Q000378:metabolism; D053499:Plasma Membrane Calcium-Transporting ATPases; D011817:Rabbits; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013194:Staining and Labeling / Q000379:methods; D013552:Swine
chemical_list: D027682:Cation Transport Proteins; D003902:Detergents; D008055:Lipids; D010713:Phosphatidylcholines; D053499:Plasma Membrane Calcium-Transporting ATPases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase