A tyrosine-based sorting signal is involved in connexin43 stability and gap junction turnover
Details
Serval ID
serval:BIB_06E11452F161
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
A tyrosine-based sorting signal is involved in connexin43 stability and gap junction turnover
Journal
Journal of Cell Science
ISSN
0021-9533 (Print)
Publication state
Published
Issued date
06/2003
Volume
116
Number
Pt 11
Pages
2213-22
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Jun 1
Research Support, Non-U.S. Gov't --- Old month value: Jun 1
Abstract
The gap junction protein connexin43 is known to have a rapid turnover, involving degradation by both the proteasomal and lysosomal systems, but the structural features of connexin43 that govern these actions are not known. The connexin43 C-terminal sequence contains a proline-rich region corresponding to the consensus of a protein-protein interaction PY-motif (xPPxY), and an overlapping putative tyrosine-based sorting signal (Yxxphi; =hydrophobic), known to play a role in the intracellular trafficking of many membrane proteins. As both motifs may control turnover of connexin43, we used a combination of metabolic radiolabelling, immuno-precipitation and functional assays to determine the possible role of these motifs in controlling degradation of human connexin43 expressed in SKHep1 cells. Mutation V289D in the tyrosine-based sorting motif increased the steady-state pool of connexin43 by approximately 3.5-fold, while mutation P283L in the PY-motif produced a comparatively modest augmentation (1.7-fold). No additive effect was observed when the overlapping tyrosine was mutated. In pulse-chase experiments, the Y286A substitution increased the half-life of connexin43 from 2 to 6 hours, indicating that the increased steady-state levels reflected reduced protein degradation. Moreover, expression at the junctional membrane, as well as gap junction-mediated intercellular communication (GJC), were nearly abolished by lysosomal inhibitors and Brefeldin A in cells expressing wild-type connexin43, but were unaffected in the tyrosine mutant. These results provide strong evidence that the tyrosine-based motif of human connexin43 is a prime determinant controlling connexin43 stability, and consequently GJC, by targeting connexin43 for degradation in the endocytic/lysosomal compartment.
Keywords
Carcinoma, Hepatocellular
Cell Line, Tumor
Connexin 43/genetics/*metabolism
Cysteine Endopeptidases/metabolism
Endosomes/metabolism
Gap Junctions/*metabolism
Humans
Liver Neoplasms
Lysosomes/metabolism
Multienzyme Complexes/metabolism
Mutagenesis/physiology
Proteasome Endopeptidase Complex
Protein Sorting Signals/*physiology
Protein Transport/physiology
Tyrosine/*metabolism
Pubmed
Web of science
Open Access
Yes
Create date
24/01/2008 13:03
Last modification date
20/08/2019 12:29