1. The mechanism of the inhibition of Na(+)-plus-K(+)-activated adenosine triphosphatase by calcium was investigated with an enzyme preparation from rabbit kidney cortex and with membranes of human erythrocytes. 2. CaATP, rather than ionic Ca(2+), acts as a competitive inhibitor, competing with MgATP in the Na(+)-plus-K(+)-activated adenosine-triphosphatase reaction. 3. There appears to be no c...

A membrane-associated thiamine triphosphatase in subcellular fractions of the rat brain is described. This enzyme is shown to be different from a less active soluble thiamine triphosphatase previously reported. It is also shown to be distinct from ATPases and from a general nucleoside triphosphatase in the tissues examined. The membraneassociated thiamine triphosphatase activity has an absolute...

A membrane-associated thiamine triphosphatase in subcellular fractions of the rat brain is described. This enzyme is shown to be different from a less active soluble thiamine triphosphatase previously reported. It is also shown to be distinct from ATPases and from a general nucleoside triphosphatase in the tissues examined. The membraneassociated thiamine triphosphatase activity has an absolute...

The incision of damaged DNA by the Escherichia coli UvrABC endonuclease requires ATP hydrolysis. Although the deduced sequence of the UvrB protein suggests a putative ATP binding site, no nucleoside triphosphatase activity is demonstrable with the purified UvrB protein. The UvrB protein is specifically proteolyzed in E. coli cell extracts to yield a 70 kD fragment, referred to as UvrB*, which h...

PURPOSE To explore the potential survival-promoting effect of inosine on axotomized retinal ganglion cells (RGCs) of adult rats in vivo. METHODS The left optic nerves (ON) in the subject rats were transected at 1.5 mm from the optic disc. Repeated intraperitoneal injections or single intraocular injection of inosine were administered. The RGCs were retrogradely labeled with a gold fluorescent...

The proventricular surface epithelial cells were positive for both acid and neutral mucins and stained intensive for acid phosphatase and adenosine triphosphatase. The proprial gland cells revealed histochemical distribution and activity of various enzymes and lipids similar to that of the submucosal gland cells. However, the ductular cells of the submucosal glands showed comparatively stronger...

1. Influx and efflux of catecholamine and adenosine triphosphatase activity were studied in storage vesicles of bovine adrenal medulla. 2. In the absence of ATP the influx of catecholamine was slow and was not influenced by various anions, whereas the efflux increased in the sequence of anions given by the lyotrophic series. 3. In the presence of ATP the efflux was enhanced compared with that i...

Purines are ubiquitous endogenous cellular metabolites that have been postulated as neurotransmitters or neuromodulators in the nervous system. Recently, we showed that a low-molecular-mass component present in liver-conditioned medium selectively enhances the adrenergic properties of dissociated chicken sympathetic neurons in culture. We report here that this substance is inosine, a purine met...

The purine nucleoside inosine has been shown to induce axon outgrowth from primary neurons in culture through a direct intracellular mechanism. For this study, we investigated the effects of inosine in vivo by examining whether it would stimulate axon growth after a unilateral transection of the corticospinal tract. Inosine applied with a minipump to the rat sensorimotor cortex stimulated intac...