Electrogenic epinephrine transport in chromaffin granule ghosts

Biochemistry ◽  
1980 ◽  
Vol 19 (13) ◽  
pp. 2938-2942 ◽  
Author(s):  
Jane Knoth ◽  
Kathleen Handloser ◽  
David Njus
Keyword(s):  
Chromaffin Granule ◽  
Chromaffin Granule Ghosts

scholarly journals Characterization of ATP Transport into Chromaffin Granule Ghosts

1996 ◽  
Vol 271 (29) ◽  
pp. 17132-17138 ◽  
Author(s):  
Laurie A. Bankston ◽  
Guido Guidotti
Keyword(s):  
Chromaffin Granule ◽  
Chromaffin Granule Ghosts

Stoichiometry of hydrogen ion-linked dopamine transport in chromaffin granule ghosts

Biochemistry ◽  
1981 ◽  
Vol 20 (23) ◽  
pp. 6625-6629 ◽  
Author(s):  
Jane Knoth ◽  
Michael Zallakian ◽  
David Njus
Keyword(s):  
Hydrogen Ion ◽  
Chromaffin Granule ◽  
Dopamine Transport ◽  
Chromaffin Granule Ghosts

scholarly journals Transport of catecholamines by resealed chromaffin-granule ‘ghosts’

1974 ◽  
Vol 144 (2) ◽  
pp. 311-318 ◽  
Author(s):  
J H Phillips
Keyword(s):  
Chromaffin Granule ◽  
Rapid Purification ◽  
Chromaffin Granule Ghosts

A method is described for the preparation of resealed chromaffin-granule ‘ghosts’. The lysis and rapid purification procedures provide ‘ghosts’ in approximately 70% yield from crude granules; the preparation contains 0.1μmol of catecholamine/mg of protein (as compared with 2.8μmol/mg in unlysed granules), of which about one third is inside the ‘ghosts’. The ‘ghosts’ retain their ability to accumulate catecholamines, a process dependent on Mg-ATP and inhibited by reserpine, and a simple assay for this transport is described.

scholarly journals Isolation of ATPase I, the proton pump of chromaffin-granule membranes

1985 ◽  
Vol 231 (3) ◽  
pp. 557-564 ◽  
Author(s):  
J M Percy ◽  
J G Pryde ◽  
D K Apps
Keyword(s):  
Proton Pump ◽  
Alkylating Agents ◽  
Proton Translocation ◽  
Phase Segregation ◽  
Chromaffin Granule ◽  
Chromaffin Granule Ghosts ◽  
Triton X ◽  
Atpase Ii ◽  
Hydrolysis Of ◽  
Granule Matrix

Chromaffin-granule membranes contain two ATPases, which can be separated by (NH4)2SO4 fractionation after solubilization with detergents, or by phase segregation in Triton X-114. ATPase I (Mr 400000) is inhibited by trialkyltin, quercetin and alkylating agents, and hydrolyses both ATP and ITP. It contains up to five types of subunit, including a low-Mr hydrophobic polypeptide that reacts with dicyclohexylcarbodi-imide; these subunits are unrelated to those of mitochondrial F1F0-ATPase, as judged by size and reaction with antibodies. ATPase II (Mr 140000) is inhibited by vanadate, and is specific for ATP; it has not been extensively purified. Proton translocation by resealed chromaffin-granule ‘ghosts’, measured by uptake of methylamine or by quenching of the fluorescence of 9-amino-6-chloro-2-methoxyacridine, is supported by the hydrolysis of ATP or ITP, and inhibited by quercetin or alkylating agents, but not by vanadate. ATPase I must therefore be the proton translocator involved in the uptake of catecholamines and possibly of other components of the chromaffin-granule matrix, whereas ATPase II does not translocate protons.

scholarly journals Reduction of membrane-bound dopamine β-hydroxylase from the cytoplasmic surface of the chromaffin-granule membrane

1982 ◽  
Vol 202 (3) ◽  
pp. 759-770 ◽  
Author(s):  
M Grouselle ◽  
J H Phillips
Keyword(s):  
Accumulation Rate ◽  
Chromaffin Granule ◽  
Cytoplasmic Surface ◽  
Dopamine Beta Hydroxylase ◽  
Matrix Surface ◽  
The Matrix ◽  
Granule Membrane ◽  
Membrane Bound ◽  
Chromaffin Granule Ghosts ◽  
Low Ionic Strength

Resealed bovine chromaffin-granule ‘ghosts’ were used for assaying the membrane-bound form of dopamine beta-hydroxylase. Hydroxylation of the substrate tyramine is dependent on its accumulation within the ‘ghosts’, where the active site of the enzyme is located. Free tyramine in the medium is at a low concentration, low ionic strength and a relatively high pH (7.0), so that even in the presence of a reducing agent (co-reductant) the unaccumulated amine is hydroxylated at a negligible rate. ‘Ghosts’ contain an endogenous co-reductant, which is shown to be catecholamine remaining in the membrane itself after granule lysis. Catecholamine that is free in solution in the medium or in the interior of the ‘ghosts’ is not effective as co-reductant, nor is ascorbate, in contrast with the situation with soluble dopamine beta-hydroxylase. Ferrocyanide is an active co-reductant, however, giving a hydroxylation rate approximately equal to the tyramine accumulation rate: it does not enter the ‘ghosts’, nor does the enzyme appear to utilize ferrocyanide sealed inside the ‘ghosts’. A mechanism must therefore exist for transferring electrons across the membrane from the cytoplasmic surface to the matrix surface. NADH is not an electron donor for the enzyme, nor is cytochrome b-561 involved.

scholarly journals Hydroxytryptamine transport by the bovine chromaffin-granule membrane

1978 ◽  
Vol 170 (3) ◽  
pp. 673-679 ◽  
Author(s):  
J H Phillips
Keyword(s):  
Low Ph ◽  
Ph Gradient ◽  
Chromaffin Granule ◽  
Concentration Gradients ◽  
Granule Membrane ◽  
Chromaffin Granule Ghosts

5-Hydroxytryptamine is accumulated by resealed chromaffin-granule ‘ghosts’ if a pH gradient (acid inside) is imposed across their membranes by preincubating them at low pH. This uptake, like that driven by MgATP, is reserpine- and uncoupler-sensitive. This strongly suggests that catecholamines are taken up by intact granules in response to a pH gradient. In line with this, it is shown that 5-hydroxytryptamine decreases the pH gradient generated in the presence of MgATP, an effect that is inhibited by reserpine; nigericin, which discharges the pH gradient in the presence of K+, inhibits uptake. Permeant anions, however, also inhibit uptake. It is suggested that this may be because they permit equilibration of amine cations directly across the membrane, down concentration gradients.

Sign in / Sign up

Export Citation Format

Share Document