Affinity labeling and localization of the ATP binding site in the (Na+,K+)-ATPase
Abstract:
The (Na+,K+)-ATPase has been covalently labeled with oxidized ATP. The extent of oxidized ATP incorporation which inactivates the enzyme corresponds to one nucleotide site per equivalent of ouabain binding site. ATP and ADP protect against the covalent labeling by oxidized ATP; the dissociation constants for the protective effects of ATP and ADP are 0.6 mM and 2.5 mM, respectively. The covalent incorporation is accelerated by K+ and by ouabain in the presence of Mg2+. The site of incorporation of oxidized ATP is located on a Mr = 58,000 fragment situated at the COOH-terminal end of the Mr = 94,000 alpha chain, while the phosphorylation site and the ouabain site are in the other (NH2-terminal) part of the chain.
Related Concept Videos
Ligand Binding and Linkage
ATP Driven Pumps I: An Overview
There are four main types of ATP-driven pumps - P-type, V-type, F-type, and ABC transporter. All these pumps are of varying complexities and are...
ATP Synthase: Mechanism
ATP Driven Pumps II: P-type Pumps
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
ATP Driven Pumps III: V-type Pumps
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...


