Stoichiometry of lipid-protein interaction assessed by hydrophobic photolabeling.
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).
Villamil Giraldo
Ana María
AM
Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956.C1113AAD, Buenos Aires, Argentina.
Castello
Pablo Raúl
PR
González Flecha
F Luis
FL
Moeller
Jesper V
JV
Delfino
José María
JM
Rossi
Juan Pablo F C
JP
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
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