title: Inactivation of the Na,K-ATPase by modification of Lys-501 with 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS).
abstract: The sodium pump or Na,K-ATPase, maintains the Na+ and K+ gradients across eukaryotic cell membranes at the expense of ATP. Incubation of purified canine renal Na,K-ATPase with 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS) inhibited the ATPase activity. Both the labeling of the protein and the loss of ATPase activity were prevented by co-incubation with ADP (acting as an ATP analog) or KCl. Only the alpha-subunit was labeled by SITS. The alpha-subunit from the inhibited enzyme was extensively digested with trypsin, and SITS-labeled peptides were purified by reverse-phase HPLC and sequenced. The amino acid sequence determined, His-Leu-Leu-Val-Met-X-Gly-Ala-Pro-Glu, indicated that SITS modifies Lys-501 (X) on the alpha-subunit of Na,K-ATPase.
authors.affiliation: Department of Physiology, University of Pennsylvania, Philadelphia 19104-6085.
authors.forename: C H
authors.initials: CH
authors.lastname: Pedemonte
authors.forename: T L
authors.initials: TL
authors.lastname: Kirley
authors.forename: M J
authors.initials: MJ
authors.lastname: Treuheit
authors.forename: J H
authors.initials: JH
authors.lastname: Kaplan
mesh_terms: D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D004285:Dogs; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D008239:Lysine; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D011189:Potassium Chloride / Q000494:pharmacology; D011487:Protein Conformation; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects* / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000244:Adenosine Diphosphate; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; D000254:Sodium-Potassium-Exchanging ATPase; D008239:Lysine