Inhibition of adenosine triphosphatase, 5-hydroxytryptamine transport and proton-translocation activities of resealed chromaffin-granule 'ghosts'.

ABSTRACT: 1. Highly purified resealed chromaffin-granule ;ghosts' were assayed for ATPase and ATP-driven H(+)-translocation and 5-hydroxytryptamine-uptake activities, and for 5-hydroxytryptamine uptake driven by an imposed transmembrane H(+)-gradient. The effects of several inhibitors on these activities were studied. 2. Dicyclohexylcarbodi-imide inhibits all of these activities, but not in parallel; at low concentrations it decreases the permeability of the membrane to protons. 3. 4-Chloro-7-nitrobenzofuran (Nbf-Cl) and silicotungstate inhibit ATP-dependent activities, without effect on 5-hydroxytryptamine uptake driven by an imposed H(+)-gradient. 4. Tributyltin chloride inhibits all of the activities. 5. Treatment of the ;ghosts' with low concentrations of urea inhibits 5-hydroxytryptamine uptake and ATP-dependent generation of a transmembrane H(+)-gradient, without inhibiting ATPase activity. 6. Nbf-Cl and silicotungstate are without effect on the rate of leakage of 5-hydroxytryptamine from preloaded ;ghosts', whereas dicyclohexylcarbodi-imide and tributyltin chloride accelerate the rate of leakage. 7. Treatment of the membranes with (14)C-labelled Nbf-Cl labels several proteins; membranes treated with dicyclohexyl[(14)C]carbodi-imide are labelled predominantly in a protein of low molecular weight, which may be analogous to the mitochondrial H(+)-conducting proteolipid. 8. It is concluded that Nbf-Cl and silicotungstate inhibit the H(+)-translocating ATPase of the granule membrane; that dicyclohexylcarbodi-imide inhibits the ATPase, and inhibits 5-hydroxytryptamine accumulation by accelerating leakage of the amine; and that the effects of tributyltin chloride are due to inhibition of the ATPase, and collapse of the transmembrane H(+)-gradient through OH(-)-anion exchange.

SUBMITTER: Apps DK 

PROVIDER: S-EPMC1162091 | biostudies-other | 1980 Aug

REPOSITORIES: biostudies-other