Metabolic pathways coupled to H+ transport in turtle urinary bladder.

S Kelly; T E Dixon; Q Al-Awqati

doi:10.1007/bf01870240

Home/Archive/PubMed

PubMed · 6446607

Metabolic pathways coupled to H+ transport in turtle urinary bladder.

S Kelly·T E Dixon·Q Al-Awqati

View original source ↗Export metadata ↓

Abstract

Active H+ transport in the turtle urinary bladder is mediated by an ATPase. Although the source of ATP is usually mitochondrial oxidative phosphorylation, it is possible because of intracellular compartmentalization or cellular heterogeneity that one metabolic pathway exclusively provides ATP to the pump. To examine this we performed several types of experiments. In one, the coupling between the rate of transport and the rate of oxidation of 14C-labeled substrates was studied. We found that there was coupling between H+ transport and glucose, butyrate oleate, and beta-OH-butyrate oxidation. In another set of experiments we depleted turtle bladders of their endogenous substrates and tested the effect of a number of substrates on the rate of transport. We found that glucose, pyruvate, lactate, actetate, butyrate and beta-OH butyrate all stimulated H+ transport. In a third set of experiments we found no coupling between H+ transport and lactate production. Finally, we found that reduction of H+ transport by mucosal acidification resulted in an increase in epithelial cell ATP concentrations and a decrease in ADP levels. These results suggest that the H+ pump receives its ATP from carbohydrate and fatty acid oxidation. The changes in ATP and ADP levels provide an initial explanation for the coupling of H+ transport to the rate of cellular oxidative metabolism.

Explore related subjects

Adenine Nucleotides Adenosine Triphosphatases Animals Biological Transport, Active Butyrates Glucose Hydrogen-Ion Concentration Hydroxybutyrates Kinetics Lactates Male Oleic Acids Oxygen Consumption Turtles Urinary Bladder Journal Article Research Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

S Kelly, T E Dixon, Q Al-Awqati. 1980-06-15. Metabolic pathways coupled to H+ transport in turtle urinary bladder.. https://doi.org/10.1007/bf01870240

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Functional interrogation of the kinome using nucleotide acyl phosphates.

The central role of protein kinases in signal transduction pathways has generated intense interest in targeting these enzymes for a wide range of therapeutic indications. Here we report a method for identifying and quantifying protein kinases in any biological sample or tissue from any species. The procedure relies on acyl phosphate-containing nucleotides, prepared from a biotin derivative and ATP or ADP. The acyl phosphate probes react selectively and covalently at the ATP binding sites of at least 75% of the known human protein kinases. Biotinylated peptide fragments from labeled proteomes are captured and then sequenced and identified using a mass spectrometry-based analysis platform to determine the kinases present and their relative levels. Further, direct competition between the probes and inhibitors can be assessed to determine inhibitor potency and selectivity against native protein kinases, as well as hundreds of other ATPases. The ability to broadly profile kinase activities in native proteomes offers an exciting prospect for both target discovery and inhibitor selectivity profiling.

Adenine Nucleotides↗

PubMed2007

Revised procedures for yeast metabolites extraction: application to a glucose pulse to carbon-limited yeast cultures, which reveals a transient activation of the purine salvage pathway.

In this study we have revised our original procedure of yeast metabolites extraction. We showed that: (a) less than 5% of intracellular metabolites leaks out during the step of rapid arrest of cellular metabolism by quenching yeast cells into a 60% methanol solution kept at -40 degrees C; and (b) with a few exception, the stability of metabolites were not altered during the 3 min boiling procedure in a buffered ethanol solution. However, there was a loss of external added metabolites of 5-30%, depending on the type of metabolites. This was mainly attributable to their retention on cellular debris after ethanol treatment, which prevented centrifugation of the cellular extracts before evaporation of ethanol. We further simplified our previous high-performance ionic chromatography (HPIC) techniques for easier, more reliable and robust quantitative measurements of organic acids, sugar phosphates and sugar nucleotides, and extended these techniques to purine and pyrimidine bases, using a variable wavelength detector set at 220 and 260 nm in tandem with a pulsed electrochemical or suppressed conductivity detector. These protocols were successfully applied to a glucose pulse to carbon-limited yeast cultures on purines metabolism. This study showed that glucose induced a fast activation of the purine salvage pathway, as indicated by a transient drop of ATP and ADP with a concomitant rise of IMP and inosine. This metabolic perturbation was accompanied by a rapid increase in the activity of the ISN1-encoded specific IMP-5'-nucleotidase. The mechanism of this activation remains to be determined.

Adenine Nucleotides↗

PubMed2006

Nucleotide recognition by the cytoplasmic domain of the human chloride transporter ClC-5.

The ubiquitous CBS domains, which are found as part of cytoplasmic domains in the ClC family of chloride channels and transporters, have previously been identified as building blocks for regulatory nucleotide-binding sites. Here we report the structures of the cytoplasmic domain of the human transporter ClC-5 in complex with ATP and ADP. The nucleotides bind to a specific site in the protein. As determined by equilibrium dialysis, the affinities for ATP, ADP and AMP are in the high micromolar range. Point mutations that interfere with nucleotide binding change the transport behavior of a ClC-5 mutant expressed in Xenopus laevis oocytes. Our results establish the structural and energetic basis for the interaction of ClC-5 with nucleotides and provide a framework for future investigations.

Adenine Nucleotides↗