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Biochemistry. 1981 Nov 10;20(23):6625-9.

Stoichiometry of H+-linked dopamine transport in chromaffin granule ghosts.

Abstract

A proton-translocating adenosinetriphosphatase in adrenal medullary chromaffin granule ghosts can generate either a membrane potential (inside positive) or a pH gradient (inside acid). Dopamine uptake occurs in response to both the membrane potential and the pH gradient. The natural logarithm of the dopamine concentration gradient [In (Din/Dout)] is linearly related to the membrane potential with a slope of F/(RT). This dependence is not affected by the pH of the medium. In (Din/Dout) is linearly dependent on In ([H+]in/[H+]out) with a slope of 2. These results indicate that dopamine is taken up via an exchange diffusion or antiport mechanism. The stoichiometry of this exchange is two H+/dopamine cation and is independent of pH.

PMID:
6458332
DOI:
10.1021/bi00526a016
[Indexed for MEDLINE]

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