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Comparative Incorporation of Proenkephalin‐Derived Peptides, Chromogranin A, and Dopamine β‐Hydroxylase into Chromaffin Vesicles
Author(s) -
Wilson Steven P.,
Corcoran James J.,
Kirshner Norman
Publication year - 1991
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1991.tb08231.x
Subject(s) - proenkephalin , chromaffin cell , vesicle , chromogranin a , adrenal medulla , biochemistry , enkephalin , chemistry , dopamine , catecholamine , biology , endocrinology , medicine , membrane , immunology , receptor , immunohistochemistry , opioid
The incorporation of enkephalin‐containing peptides (ECPs) derived from proenkephalin into chromaffin vesicles was examined in primary cultures of adrenal medullary chromaffin cells. Cells were pulse‐labeled with [ 35 S]methionine and chased for periods up to 24 h. Chromaffin vesicles in cell homogenates were then fractionated by density gradient centrifugation and the presence of [ 35 S]Met‐enkephalin sequences in gradient fractions determined. 35 S‐ECPs were incorporated into particles suggestive of immature vesicles within 1–2 h after radiolabeling. Vesicle maturation, measured by co‐equilibration of 35 S‐ECPs and total ECPs in the gradients, was complete within 9–12 h and was unaffected by treatments that increase proenkephalin synthesis. Incorporation of [ 35 S]chromogranin A into chromaffin vesicles followed a similar time course, but 35 S‐labeled dopamine β‐hydroxylase was much more slowly incorporated, possibly reflecting differences in incorporation of membrane and soluble components. In summary, the data demonstrate that ECPs are rapidly sequestered in immature chromaffin vesicles, a process unaltered by changing rates of proenkephalin synthesis.