Channelpedia

PubMed 19138172


Referenced in Channelpedia wiki pages of: none

Automatically associated channels: KChip1 , KChip2a , Kv1.4 , Kv3.1 , Kv4.2



Title: A VAMP7/Vti1a SNARE complex distinguishes a non-conventional traffic route to the cell surface used by KChIP1 and Kv4 potassium channels.

Authors: Sarah E Flowerdew, Robert D Burgoyne

Journal, date & volume: Biochem. J., 2009 Mar 15 , 418, 529-40

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/19138172


Abstract
The KChIPs (K(+) channel-interacting proteins) are EF hand-containing proteins required for the traffic of channel-forming Kv4 K(+) subunits to the plasma membrane. KChIP1 is targeted, through N-terminal myristoylation, to intracellular vesicles that appear to be trafficking intermediates from the ER (endoplasmic reticulum) to the Golgi but differ from those underlying conventional ER-Golgi traffic. To define KChIP1 vesicles and the traffic pathway followed by Kv4/KChIP1 traffic, we examined their relationship to potential SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) proteins mediating the trafficking step. To distinguish Kv4/KChIP1 from conventional constitutive traffic, we compared it to the traffic of the VSVG (vesicular-stomatitis virus G-protein). Expression of KChIP with single or triple EF hand mutations quantitatively inhibited Kv4/KChIP1 traffic to the cell surface but had no effect on VSVG traffic. KChIP1-expressing vesicles co-localized with the SNARE proteins Vti1a and VAMP7 (vesicle-associated membrane protein 7), but not with the components of two other ER-Golgi SNARE complexes. siRNA (small interfering RNA)-mediated knockdown of Vti1a or VAMP7 inhibited Kv4/KChIP1traffic to the plasma membrane in HeLa and Neuro2A cells. Vti1a and VAMP7 siRNA had no effect on VSVG traffic or that of Kv4.2 when stimulated by KChIP2, a KChIP with different intrinsic membrane targeting compared with KChIP1. The present results suggest that a SNARE complex containing VAMP7 and Vti1a defines a novel traffic pathway to the cell surface in both neuronal and non-neuronal cells.