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Inactivation of the catecholamine transporter during the preparation of chromaffin granule membrane ‘ghosts’
Author(s) -
Gasnier Bruno,
Scherman Daniel,
Henry Jean-Pierre
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80222-3
Subject(s) - catecholamine , granule (geology) , chemistry , transporter , chromaffin cell , biophysics , adrenal medulla , biochemistry , biology , neuroscience , gene , paleontology
The activity of the catecholamine transporter of chromaffin granules and the binding to these vesicles of reserpine, a transporter inhibitor, decrease during ghost preparation. In contrast, the number of binding sites of dihydrotetrabenazine, another transporter ligand, is constant. Dihydrotetrabenazine thus binds to an inactive transporter whereas reserpine binds only to active vesicles. Inactivation occurs during lysis of the granules, possibly because of an incomplete resealing. The turnover number of the transporter, determined by dividing the uptake activity by the density of dihydrotetrabenazine binding sites, has a maximal value (140 molecules/min) in intact granules. The reserpine to dihydrotetrabenazine binding ratio (10–25%) is an estimate of the proportion of correctly resealed vesicles.