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A highly Ca2+-sensitive pool of vesicles is regulated by protein kinase C in adrenal chromaffin cells.

Authors
  • Yang, Yan
  • Udayasankar, Sangeetha
  • Dunning, James
  • Chen, Peng
  • Gillis, Kevin D
Type
Published Article
Journal
Proceedings of the National Academy of Sciences of the United States of America
Publication Date
Dec 24, 2002
Volume
99
Issue
26
Pages
17060–17065
Identifiers
PMID: 12446844
Source
Medline
License
Unknown

Abstract

We have used flash photolysis of caged Ca2+ and membrane capacitance measurements to probe exocytosis in chromaffin cells at low concentrations of intracellular Ca2+ ([Ca2+]i) (<10 microM). We observed a small pool of granules that is more sensitive to [Ca2+]i than the previously described "readily releasable pool." Upon activation of PKC, this "highly Ca2+-sensitive pool" is enhanced in size to a greater extent than the readily releasable pool but is eliminated upon expression of a C-terminal deletion mutant (Delta9) of synaptosome-associated protein of 25 kDa (SNAP-25). Thus, in chromaffin cells, PKC enhances exocytosis both by increasing the number of readily releasable vesicles and by shifting vesicles to a highly Ca2+-sensitive state, enabling exocytosis at sites relatively distant from Ca2+ channels.

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