Stoichiometry of lipid-protein interactions assesed by hydrophobic photolabeling

VILLAMIL GIRALDO A.M.; CASTELLO P.R.; GONZÁLEZ FLECHA F.L.; MOELLER J.V.; DELFINO J.M.; ROSSI J.P.F.C

FEBS LETTERS

Elsevier

Año: 2006 vol. 580 p. 607 - 612

0014-5793

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).