Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An ATPase stimulated by HCO - ions and other oxybases and inhibited by SCN- has been found in main excretory duct of rat submaxillary gland, a tissue, capable of actively secreting HCO - 3 ions. No such ATPase was found in the rabbit duct, which normally does not secrete HCO - 3. The HCO - 3 ATPase was localized in the plasma membrane fraction of the homogenate, as evidenced by the marker 5'-nucleotidase. The activities of the HCO - 3 ATPase increased in metabolic alkalosis and decreased in metabolic acidosis in parallel to secretion of HCO - 3 and K+ ions by the duct epithelium. These findings provide further evidence that the membrane-bound HCO - 3 ATPase is involved in active H+/HCO - 3 transport.
 ...
PMID:H+ transport and membrane-bound HCO - 3 ATPase in salivary duct epithelium. 0 8

An HCO-3-activated and SCN--inhibited ATPase (ATP phosphohydrolase, EC 3.6.1.3) found in homogenates of intestinal mucosa of the eel was solubilized by Triton X-100. Optimal HCO-3-concentration and pH for the enzyme were 25 mM and 8.7, respectively. HCO-3-ATPase activity in both homogenate and solubilized preparations increased after seawater adaptation. This adaptive increase in enzyme activity was also observed in the gills and the kidney. The HCO-3-ATPase seems to be related to transport mechanisms, especially for Cl-, in osmoregulatory surfaces of the eel.
 ...
PMID:HCO-3-activated adenosine triphosphatase in intestinal mucosa of the eel. 0 50

By in vitro experiments on rabbit bladder, we reassessed the traditional view that mammalian urinary bladder lacks ion transport mechanisms. Since the ratio of actual-to-nominal membrane area in folded epithelia is variable and hard to estimate, we normalized membrane properties to apical membrane capacitance rather than to nominal area (probably 1 muF approximately 1 cm2 actual area). A new mounting technique that virtually eliminates edge damage yielded resistances up to 78,000 omega muF for rabbit bladder, and resistances for amphibian skin and bladder much higher than those usually reported. This technique made it possible to observe a transport-related conductance pathway, and a close correlation between transepithelial conductance (G) and short-circuit current (Isc) in these tight epithelia. G and Isc were increased by mucosal (Na+) [Isc approximately 0 when (Na+) approximately 0], aldosterone, serosal (HCO-3) and high mucosal (H+); were decreased by amiloride, mucosal (Ca++), ouabain, metabolic inhibitors and serosal (H+); and were unaffected by (Cl-) and little affected by antidiuretic hormone (ADH). Physiological variation in the rabbits' dietary Na+ intake caused variations in bladder G and Isc similar to those caused by the expected in vivo changes in aldosterone levels. The relation between G and Isc was the same whether defined by diet changes, natural variation among individual rabbits, or most of the above agents. A method was developed for separately resolving conductances of junctions, basolateral cell membrane, and apical cell membrane from this G--Isc relation. Net Na+ flux equalled Isc. Net Cl- flux was zero on short circuit and equalled only 25% of net Na+ flux in open circuit. Bladder membrane fragments contained a Na+-K+-activated, ouabain-inhibited ATPase. The physiological significance of Na+ absorption against steep gradients in rabbit bladder may be to maintain kidney-generated ion gradients during bladder storage of urine, especially when the animal is Na+-depleted.
 ...
PMID:Na+ transport by rabbit urinary bladder, a tight epithelium. 0 12

An ATPase stimulated by HCO-3ions and other oxybases and inhibited by SCN- has been found in main excretory duct of rat submaxillary gland, a tissue, capable of actively secreting HCO-3ions. No such ATPase was found in the rabbit duct, which normally does not secrete HCO-3. The HCO-3ATPase was localized in the plasma membrane fraction of the homogenate, as evidenced by the marker 5'nucleotidase. The activities of the HCO-3ATPase increased in metabolic alkalosis and decreased in metabolic acidosis in parallel to secretion of HCO-3 and K+ ions by the rat salivary duct epithelium. In renal cortex tissue, where HCO-3 is actively reabsorbed respectively H+ is secreted, there was also found a parallel change in the activity of the HCO-3ATPase and the rate of active H+ secretion. These findings provide further evidence that the membrane-bound HCO-3ATPase is involved in active H+/HCO-3 transport. The HCO-3ATPase is not only stimulated by HCO-3 but also by other non transportable oxybases, a finding which indicates H+ rather than HCO-3 being the actively transported component of the buffer system. Small concentrations of K+ ions decrease the Km for HCO-3 and thus yield stimulation of the HCO-3-ATPase. Thport changing in parallel with that of H+/HCO-3 may be taken as indicative for a coupled K+-H+-exchange mechanism to which the HCO-3ATPase is linked.
 ...
PMID:The role of HCO3-stimulated ATPase in buffer transport. 1 63

An ATPase is demonstrated in plasma membrane fractions of goldfish gills. This enzyme is stimulated by Cl- and HCO-3, inhibited by SCN-. Biochemical characterization shows that HCO-3 stimulation (Km = 2.5 mequiv./l) is specifically inhibited in a competitive fashion by SCN- (Ki = 0.25 mequiv./l). This residual Mg2+-dependent activity is weakly affected by SCN-. In the microsomal fraction chloride stimulation of the enzyme occurs in the presence of HCO-3 (Km for chloride = 1 mequiv/l); no stimulation is observed in the absence of HCO-3. Thiocyanate exhibits a mixed type of inhibition (Ki = 0.06 mequiv./l) towards the Cl- stimulation of the enzyme. Bicarbonate-dependent ATPase from the mitochondrial fraction is stimulated by Cl-, but this enzyme has a relatively weak affinity for this substrate (Km = 14 mequiv./l).
 ...
PMID:A Cl-/HCO-3-ATPase in the gills of Carassius auratus. Its inhibition by thiocyanate. 1 77

The HCO-3-stimulated Mg2+ -ATPase activity in red cell ghost fragments was investigated. Increasing the HCO-3 concentration in the incubation medium resulted in increased ATPase activity. NaHCO3 appeared to be more effective than KHCO3 in this regard. The ATPase activities were slightly stimulated by increases in ionic strength and utilized ITP almost as readily as ATP. A Mg/ATP ratio of 1.0 and a pH of 7.6 yielded maximum activity. These properties are of interest since the present enzyme is the only unquestionable instance where a HCO-3 ATPase is located in the surface membrane of a cell.
 ...
PMID:Properties of the HCO-3-stimulated Mg2+ -ATPase activity in red cell membranes. 1 3

Dependence of the HCO--3-stimulated ATPase activity from nuclei and mitochondria of rat ovary ascites tumor cells on pH and concentration of bicarbonate ions was studied. PCMB, NaN3, NaCNS, NaClO4 and NaF inhibited the HCO--3-stimulated ATPase activity. The properties of HCO--3-sensitive ATPase from rat ovary ascites tumor cells were similar to that of HCO--3-ATPases from other tissues.
 ...
PMID:[HCO3-stimulated adenosine triphosphatase in rat ovarian tumor cells]. 2 52

Properties of HCO--3-stimulated ATPase from rat heart muscle nuclei were studied. The maximal activity of HCO--3-ATPase was observed at concentration of bicarbonate 25 mM. The enzyme had a pH optimum at pH 8.0-8.5. Bicarbonate stimulated the ATPase activity only in presence of Mg2+, Mn2+ and Zn2+, Co2+, Cd2+ and Ca2+ were ineffective. NaCO3 and Na2SO3 at concentration 30 mM stimulated the nuclear ATPase activity by 20% and 81%, respectively. Anions N3--, scn--, clO--4, and I-- inhibited both Mg2+-ATPase and HCO--3-ATPase. HSO--3 and SO2--4 ions did not affect the nuclear ATPase activity.
 ...
PMID:[Anion-sensitive nuclear ATPase of the rat heart]. 2 54

The disulfonic stilbene (4-acetamido-4'-isothiocyano-2,2'-disulfonic stilbene) is found to be more potent than acetazolamide as an anion transport inhibitor in the turtle bladder, but less potent than acetazolamide as a carbonic anhydrase inhibitor. The anion-dependent (HCO-3,Cl-) moiety of the short-circuiting current is eliminated by 4-acetamido-4'-isothiocyano-2,2'-disulfonic stilbene, but only after its addition to the serosal bathing fluid. Whereas 4-acetamido-4'-isothiocyano-2,2'-disulfonic stilbene has no effect on Na+ transport across the bladder, it is more potent than ouabain as an inhibitor of microsomal (Na+ + K+)-ATPase of both turtle bladder and eel electric organ.
 ...
PMID:Effects of 4-acetamido-4'-isothiocyano-2,2-disulfonic stilbene on ion transport in turtle bladders. 12 57

Light fractions of homogenates of rat heart, diaphragm, lung, liver, kidney, spleen, muscle, brain, gastric mucosa and of red blood cell membranes contained HCO3-stimulated ATPase. ATPase activity was increased by 15-77% by adding 25 mM HCO-3.
 ...
PMID:[HCO3-stimulated ATPase from rat tissue homogenates]. 12 70


1 2 3 4 5 6 7 8 9 10 Next >>