We have used isolated embryonic photoreceptor cells as a model system with which to examine the mechanisms responsible for the development and maintenance of asymmetric Na+,K+-ATPase (ATPase) distribution. Photoreceptor precursors, which appear round and process free at culture onset, develop structural and molecular properties similar to those of photoreceptor cells in vivo. ATPase, recognized...

The sarcoplasmic reticulum of skeletal muscle contains anionic phospholipids as well as the zwitterionic phosphatidylcholine and phosphatidylethanolamine. Here we study the effects of anionic phospholipids on the activity of the Ca2+-ATPase purified from the membrane. Reconstitution of the Ca2+-ATPase into dioleoylphosphatidylserine [di(C18:1)PS] or dioleoylphosphatidic acid [di(C18:1)PA] leads...

Particles 30 to 40 A in diameter are attached to the external surface of negatively stained membrane vesicles formed by the ATPase of sarcoplasmic reticulum. These particles are identical with the surface particles of isolated, intact sarcoplasmic reticulum first described by Ikemoto et ~2. (IKEMOTO, N., SRETER, F. A., AND GERGELY, J. (1966) Fed. Proc. 25, 465). Tryptic digestion was used in an...

The mycotoxin, cyclopiazonic acid (CPA), inhibits the Ca2+-stimulated ATPase (EC 3.6.1.38) and Ca2+ transport activity of sarcoplasmic reticulum (Goeger, D. E., Riley, R. T., Dorner, J. W., and Cole, R. J. (1988) Biochem. Pharmacol. 37, 978-981). We found that at low ATP concentrations (0.5-2 microM) the inhibition of ATPase activity was essentially complete at a CPA concentration of 6-8 nmol/m...

Transverse tubule (TT) membranes isolated from chicken skeletal muscle possess a very active magnesium-stimulated ATPase (Mg-ATPase) activity. The Mg-ATPase has been tentatively identified as a 102-kD concanavalin A (Con A)-binding glycoprotein comprising 80% of the integral membrane protein (Okamoto, V.R., 1985, Arch. Biochem. Biophys., 237:43-54). To firmly identify the Mg-ATPase as the 102-k...

Synthesis and assembly of most oligomeric plasma membrane proteins occurs in the ER. However, the role the ER plays in oligomerization is unknown. We have previously demonstrated that unassociated alpha and beta subunits of the Na,K-ATPase are targeted to the plasma membrane when individually expressed in baculovirus-infected Sf-9 cells. This unique property allows us to determine if assembly o...

We present evidence that Na-K-ATPase in the rat proximal tubule is directly activated by ANG II much faster than previously observed. Specifically, we show that a 2-min exposure to 0.1 and 1 nM ANG II slowed the rate of intracellular sodium accumulation in response to an increase in extracellular sodium added in the presence of gramicidin D. From these data, we show that ANG II directly stimula...

Compounds belonging to a carbazole series have been identified as potent fungal plasma membrane proton adenosine triphophatase (H+-ATPase) inhibitors with a broad spectrum of antifungal activity. The carbazole compounds inhibit the adenosine triphosphate (ATP) hydrolysis activity of the essential fungal H+-ATPase, thereby functionally inhibiting the extrusion of protons and extracellular acidif...

Vacuolar H+-ATPase (V-ATPase), a hetero-multimeric ATP-driven proton pump has recently emerged as a critical regulator of mTOR-induced amino acid sensing for cell growth. Although dysregulated activity of cell growth regulators is often associated with cancer, the prognostic significance and metabolic roles of V-ATPase in esophageal cancer progression remain unclear. Here, we show that high lev...

Disulfiram [bis(diethylthiocarbamoyl)disulphide] has been found to stimulate reversibly the Ca(2+)-ATPase of skeletal muscle sarcoplasmic reticulum. At pH 7.2, 2.1 mM ATP and 25 degrees C, ATPase activity was found to double on addition of 120 microM disulfiram. Stimulation fitted to binding of disulfiram at a single site with a Kd of 61 microM. Disulfiram had no effect on the Ca2+ affinity of ...