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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
Publisher
Proceedings of the National Academy of Sciences
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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