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Trafficking of axonal K + channels: Potential role of Hsc70
Author(s) -
Clay John R.,
Kuzirian Alan
Publication year - 2002
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.10182
Subject(s) - axoplasm , vesicle , axolemma , biophysics , chemistry , membrane potential , repolarization , membrane , biochemistry , biology , microbiology and biotechnology , electrophysiology , axon , neuroscience , myelin , central nervous system
Voltage‐gated potassium ion channels in axons underlie the repolarization phase of the membrane action potential and help to set the resting potential. In addition to being present in the axolemma, they are also found in axoplasm in small vesicles, 30–50 nm in diameter, which may serve as a reserve pool of K + channel protein (Clay and Kuzirian [2000] J Neurobiol 45:172–184). We have developed a novel technique for extracting these vesicles from axoplasm, which relies on the ability of Texas red to bind to them, thereby reducing their buoyancy so that they are amenable to pelleting by ultracentrifugation (Clay and Kuzirian [2000] J Neurobiol 45:172–184). The mechanism underlying this process may be binding of Texas red to Hsc70, which is primarily a cytosolic protein. However, a small portion of it is located on the surface of vesicles. Kinesin is also on the vesicle surface. This protein is membrane bound in our in vitro vesicle preparation when solutions that do not contain MgATP are added to extruded axoplasm. The addition of MgATP to the solution appears to release a significant amount of kinesin from the vesicles, possibly by the Hsc70‐MgATP catalysis mechanism recently proposed by Tsai et al. Published 2002 Wiley‐Liss, Inc.