Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The ionic dependence of [(3)H]-metaraminol transport by rabbit ventricular slices was studied.2. Transport was Na(+) dependent. Choline, Li(+), K(+), Rb(+) or Cs(+) could not be substituted for Na(+).3. Transport was K(+) dependent. Rb(+) and Cs(+), but not Li, could be substituted for K(+), their relative potencies being K(+) = or >Rb(+)>Cs(+)>>Li(+). Higher concentrations of K(+), Rb(+), Cs(+) and Li inhibited [(3)H]-metaraminol transport.4. The inhibitory effects on transport of either a marked reduction in the concentration of Na(+) or of omission of K(+) were rapidly reversible on exposure of slices to Krebs solution.5. The inhibitory effect of ouabain on [(3)H]-metaraminol transport was markedly time dependent, being significantly increased by preincubation with ouabain. The inhibitory action of ouabain was not affected, however, by the Na(+) concentration present during preincubation.6. An inwardly directed Na(+) gradient did not increase [(3)H]-metaraminol transport in slices in which Na(+) pumping had been prevented by 10(-5)M ouabain, 4 degrees C, omission of K(+) or by metabolic inhibition.7. These findings provide additional evidence that the Na(+) and K(+) activated adenosine triphosphatase may participate in the transport of metaraminol and related amines. In the absence of Na(+) pumping, induced Na(+) gradients were unable to produce transport of amine as would be predicted by the co-transport model proposed by Bogdanski & Brodie (1969).
 ...
PMID:Effects of Na+ and K+ on the uptake of metaraminol by rabbit ventricular slices. 425 Dec 50

1. Either l-[4,5-(3)H]leucine or [Me-(3)H]choline, or both l-[U-(14)C]leucine and [Me-(3)H]-choline, were injected into the ninth dorsal root ganglion of the frog, and peripheral transport of labelled proteins and/or phospholipids, mostly phosphatidylcholine, was studied by analysis of consecutive segments of the sciatic nerve. 2. At 25 degrees C, approx. 5% of the (3)H-labelled protein was transported at the rate of 152mm/day. The rate was temperature-dependent with the Q(10) value of 2.6. The flow was completely blocked by the local application of colchicine, but was unaffected by cytochalasin D. 3. [Me-(3)H]-Choline was incorporated into phosphatidylcholine at a comparatively slow rate, but was transported in the nerve at a rate equivalent to that for (3)H-labelled proteins. 4. The simultaneous transport of phosphatidylcholine and the protein was further supported in the double-labelling experiments by an identical transport rate of (3)H-labelled phosphatidylcholine and (14)C-labelled proteins, by their identical temperature dependence, by simultaneous blockade with colchicine, and also by the parallel distribution of the two labels in subcellular fractions. Specific radioactivities on a protein basis of both (3)H and (14)C labels were highest in microsomal subfractions enriched with Na(+)-plus-K(+)-stimulated adenosine triphosphatase and acetylcholinesterase. It is suggested that (3)H-labelled phosphatidylcholine and (14)C-labelled proteins transported in the nerve reside in the same structural entity, most probably a membrane component.
 ...
PMID:Rapid transport of phosphatidylcholine occurring simultaneously with protein transport in the frog sciatic nerve. 427 56

Phosphatidylethanolamine N-methyltransferase (PEMT) is a hepatic integral membrane protein localized to the endoplasmic reticulum (ER). PEMT catalyzes approximately 30% of hepatic phosphatidylcholine (PC) biosynthesis. Pemt-/- mice fed a high-fat diet (HFD) develop steatohepatitis. Interestingly, portions of the ER located close to the canaliculus are enriched in PEMT. Phospholipid balance and asymmetrical distribution by adenosine triphosphatase phospholipid transporting 8B1 (ATP8B1) on the canalicular membrane is required for membrane integrity and biliary processes. We hypothesized that PEMT is an important supplier of PC to the canaliculus and that PEMT activity is critical for the maintenance of canalicular membrane integrity and bile formation following HFD feeding when there is an increase in overall hepatic PC demand. Pemt+/+ and Pemt-/- mice were fed a chow diet, an HFD, or a choline-supplemented HFD. Plasma and hepatic indices of liver function and parameters of bile formation were determined. Pemt-/- mice developed cholestasis, i.e, elevated plasma bile acid (BA) concentrations and decreased biliary secretion rates of BAs and PC, during HFD feeding. The maximal BA secretory rate was reduced more than 70% in HFD-fed Pemt-/- mice. Hepatic ABCB11/bile salt export protein, responsible for BA secretion, was decreased in Pemt-/- mice and appeared to be retained intracellularly. Canalicular membranes of HFD-fed Pemt-/- mice contained fewer invaginations and displayed a smaller surface area than Pemt+/+ mice. Choline supplementation (CS) prevented and reversed the development of HFD-induced cholestasis. Conclusion: We propose that hepatic PC availability is critical for bile formation. Dietary CS might be a potential noninvasive therapy for a specific subset of patients with cholestasis.
 ...
PMID:Impaired Hepatic Phosphatidylcholine Synthesis Leads to Cholestasis in Mice Challenged With a High-Fat Diet. 3076 63