© 2004 by European Society of Cardiology
Copyright © 2004, European Society of Cardiology
Pathways for degradation of connexins and gap junctions
aDepartment of Pediatrics, Section of Hematology/Oncology, University of Chicago, 5841 S. Maryland Ave., MC 4060, Chicago, IL 60637, USA
bDepartment of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
* Corresponding author. Tel.: +1-773-834-1498; fax: +1-773-702-9881. Email address: vberthou{at}peds.bsd.uchicago.edu
Gap junctional proteins, connexins, and gap junctional plaques are short-lived. Three pathways for their degradation have been proposed: (1) misfolded/abnormally oligomerized connexins are retrogradely translocated and degraded by the proteasome through endoplasmic reticulum-associated degradation; (2) connexins (as monomers or oligomers) may traffic directly from an early secretory compartment to the lysosome for degradation without reaching the plasma membrane; (3) connexins within gap junction plaques are degraded by the lysosome after endocytotic internalization. Degradation of gap junction plaques is proteasome-dependent in some cell types. Degradation may be regulated by ubiquitinylation, phosphorylation, or polypeptide domains that act as sorting signals.
KEYWORDS Proteasome; Lysosome; Half-life; Intercellular communication; Connexin; Gap junction