Transmembrane organization of the Na+,K(+)-ATPase molecule.
The organization of the hydrophobic domain of the Na,K-ATPase in the E1 and E2 form of the enzyme has been studied by labelling with two hydrophobic photoactivable reagents 3-(trifluoromethyl)-3-(m-[125I]iodophenyl) diazirine ([125I]TID) and 1-palmitoyl-2-[11-[4-[3-(trifluoromethyl) diazirinyl] phenyl] [2-3H]undecanoyl]-sn-glycero-3-phosphorylcholine ([3H]PTPC/11). The incorporation of the reagents into the alpha-subunit but not into the beta-subunit in the E1-conformation was shown to be lower than that in the E2 form. This indicated the structural rearrangement of the alpha-subunit, which resulted in a change in the accessibility of the membrane-bound fragments for the hydrophobic labels. The set of the [125I]TID-labelled peptides of the alpha-subunit was shown to be the same for the E1 and E2 form of the enzyme: Asp68-Lys142, Ile265-Lys341, Val545-Lys589, Ser770-Lys826, Leu842-Arg880, Asn936-Arg972 and Met973-Arg999, which points to the different level of modification of the same fragments. The first results of molecular modelling of the spatial organization of the intramembrane part of Na+,K(+)-ATPase are also presented.
Modyanov
N
N
Shemyakin Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow.
Lutsenko
S
S
Chertova
E
E
Efremov
R
R
Gulyaev
D
D
D000596:Amino Acids / Q000032:analysis; D007202:Indicators and Reagents; D008566:Membranes / Q000201:enzymology; D008956:Models, Chemical; D010777:Photochemistry; D017433:Protein Structure, Secondary; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry*
D000596:Amino Acids; D007202:Indicators and Reagents; D000254:Sodium-Potassium-Exchanging ATPase