Document Actions
Phospholipid distribution around the pla ... hydrophobic photolabeling study
Phospholipid distribution around the plasma membrane calcium pump a hydrophobic photolabeling study
5378
The functions of membrane proteins are highly dependent on their phospholipid environment. In this article, we have used a hydrophobic photolabeling method to study the noncovalent interactions between plasma membrane calcium pump (PMCA) and surrounding phospholipids. With this approach, we determined (1) the number of lipid molecules in close contact with the transmembrane surface, i.e., the lipid-protein stoichiometry, and (2) the distribution of lipid molecules among different regions of the protein. PMCA was photolabeled in mixed micelles containing detergent, the phosphatidylcholine photoactivatable analog 1-palmitoyl-2-[9-[2'-[125I]iodo-4'- (trifluoromethyldiazirinyl)-benzyloxycarbonyl]-nonaoyl]-sn-glycero-3-phosphocholine, and different amounts of dimyristoyl phosphatidylcholine (PC). The stoichiometry was estimated after the extent of the labeling reaction had been independently assessed. We determined a maximum number of 17 +/- 1 molecules of PC in close contact with the transmembrane surface per PMCA molecule. In addition, a semiquantitative description of the phospholipid environment around different regions of PMCA was carried out after limited proteolysis of the photolabeled protein. The distribution of labels among the N-terminal (1-322), the central (323-660), and the C-terminal (661-1,205) regions was 26, 36, and 38%, respectively.
Villamil Giraldo AM, Castello PR, González Flecha FL, Delfino JM, Rossi JP
Cell biochemistry and biophysics
2006-01-01 00:00
44
3
431-7
Calcium-Transporting ATPases,Cation Transport Proteins,Cell Membrane,Erythrocyte Membrane,Humans,Ion Channels,Membrane Lipids,Micelles,Na(+)-K(+)-Exchanging ATPase,Peptide Fragments,Phospholipids,Plasma Membrane Calcium-Transporting ATPases,Staining and Labeling,Cation Transport Proteins,Ion Channels,Membrane Lipids,Micelles,Peptide Fragments,Phospholipids,Na(+)-K(+)-Exchanging ATPase,Calcium-Transporting ATPases,Plasma Membrane Calcium-Transporting ATPases
Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires., Buenos Aires, Argentina.
Cell Biochem. Biophys.
1085-9195
CBB:44:3:431
0
False
16679530
