Inhibition of Glycosylation Induces Formation of Open Connexin-43 Cell-to-Cell Channels and Phosphorylation and Triton X-100 Insolubility of Connexin-43 (∗)

• Published in: The Journal of biological chemistry 1995-11, Vol.270 (44), p.26581-26585
• Main Authors: Wang, Yingjian, Mehta, Parmender P., Rose, Birgit
• Format: Article
• Language: English
• Subjects: Alkaline Phosphatase; Animals; Blotting, Western; Cell Line; Connexin 43 - drug effects; Connexin 43 - isolation & purification; Connexin 43 - metabolism; Glycosylation - drug effects; Immunohistochemistry; Ion Channels - metabolism; Liver Neoplasms, Experimental; Octoxynol; Phosphorylation; Rats; Recombinant Proteins - drug effects; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Solubility; Transfection; Tunicamycin - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.44.26581

We transfected the cDNA for the cell-to-cell channel protein connexin-43 (Cx43) into Morris hepatoma H5123 cells, which express little Cx43 and lack gap junctional communication (open cell-to-cell channels). We found that cells overexpressing Cx43 nonetheless lacked open cell-to-cell channels, but that inhibition of glycosylation by tunicamycin induced open channels in these cells. Tunicamycin also induced biochemical changes in Cx43 protein; the level increased, and a considerable fraction became phosphorylated and Triton X-100 insoluble, in contrast to untreated cells where Cx43 was non-phosphorylated and Triton X-100 soluble. Although tunicamycin caused the formation of open channels, channels were not found aggregated into gap junctional plaques, as they are when they have been induced by elevation of intracellular cAMP. The results suggest that although Cx43 itself is not glycosylated, other glycosylated proteins influence Cx43 posttranslational modification and the formation of Cx43 cell-to-cell channels.