The Journal of Neuroscience, November 15, 1999, 19(22):9739-9746
Tyrosine Phosphorylation Regulates Rapid Endocytosis in Adrenal
Chromaffin Cells
Paolo G. P.
Nucifora and
Aaron P.
Fox
The University of Chicago, Department of Pharmacological and
Physiological Sciences, Chicago, Illinois 60637
Secretion of neurotransmitter at the synapse and in secretory cells
depends on the availability of vesicles for exocytosis. Rapid
endocytosis is responsible for initiating local vesicle recycling and
is essential during sustained neurotransmission. Although exocytosis is
triggered by Ca2+ influx and modulated by
serine/threonine kinases, relatively little is known about the
regulation of rapid endocytosis. Our data suggest that rapid
endocytosis is controlled by tyrosine phosphorylation. Treatment of
bovine adrenal chromaffin cells with tyrphostin 23, a protein tyrosine
kinase inhibitor, dramatically slowed the time course of rapid
endocytosis. In contrast, there was no effect on either the amount or
rate of exocytosis. Application of orthovanadate,
Zn2+, or poly(Glu, Tyr) (4:1), each of which is a
tyrosine phosphatase inhibitor, reversed the effect of tyrphostin 23 on
rapid endocytosis. Thus rapid endocytosis, like exocytosis, is subject
to regulation by intracellular signaling pathways.
Key words:
rapid endocytosis; tyrosine phosphorylation; adrenal
chromaffin cells; exocytosis; tyrphostin 23; capacitance
measurements
Copyright © 1999 Society for Neuroscience 0270-6474/99/19229739-08$05.00/0