Site-directed mutagenesis of Asp-376, the catalytic phosphorylation site, and Lys-507, the putative ATP-binding site, of the alpha-subunit of Torpedo californica Na+/K(+)-ATPase.
Point mutations of Asp-376 of the alpha-subunit of Torpedo californica Na+/K(+)-ATPase (the site of phosphorylation during the catalytic cycle) to Asn, Glu or Thr led to virtual abolishment of Na+/K(+)-ATPase activity and ouabain-binding capacity. Replacement of Lys-507 of the same subunit (the putative ATP-binding site) by Met resulted in decreases in Na+/K(+)-ATPase activity and ouabain-binding capacity. These results are in agreement with those reported for rabbit sarcoplasmic reticulum Ca2(+)-ATPase (Maruyama, K. and MacLennan, D.H. (1988) Proc. Natl. Acad. Sci. USA 85, 3314-3318).
Ohtsubo
M
M
Department of Biology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Noguchi
S
S
Takeda
K
K
Morohashi
M
M
Kawamura
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001224:Aspartic Acid; D001483:Base Sequence; D001665:Binding Sites; D005260:Female; D015870:Gene Expression; D007700:Kinetics; D008239:Lysine; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009154:Mutation; D009838:Oligodeoxyribonucleotides / Q000302:isolation & purification; D009865:Oocytes / Q000201:enzymology; D010766:Phosphorylation; D015183:Restriction Mapping; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics* / Q000378:metabolism; D014101:Torpedo; D014981:Xenopus
D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D001224:Aspartic Acid; D000255:Adenosine Triphosphate; D000254:Sodium-Potassium-Exchanging ATPase; D008239:Lysine