Cdc2-mediated phosphorylation of the gap junction protein, connexin43, during mitosis.
As cells enter mitosis, gap junctional communication with neighboring cells decreases (H. Xie et al., J. Cell Biol., 137: 203-210, 1997). Phosphorylation of the gap junction protein, connexin43 (Cx43), has been implicated in reducing junctional permeability. Cx43 contains p34cdc2 phosphorylation consensus sites in its COOH-terminal region. Accordingly, we examined the role of p34cdc2/cyclin B in Cx43 phosphorylation. Purified p34cdc2/cyclin B, or p34cdc2/cyclin B complex immunoprecipitated from mitotic cells, phosphorylated GSTCx43 in vitro. The synthetic peptide, SDPYHATTGPLSPSKDCGSPK, corresponding to amino acids 241-264 of Cx43, was also phosphorylated by p34cdc2/cyclin B in vitro. Sites phosphorylated in vitro were phosphorylated in vivo. Butyrolactone I, an inhibitor of cdc2 kinase, inhibited increases in Cx43 phosphorylation during mitosis. We conclude that phosphorylation of Cx43 by p34cdc2/cyclin B may contribute to the increased Cx43 phosphorylation and reduced gap junctional communication observed during mitosis.
Kanemitsu
M Y
MY
Molecular Biology and Virology Laboratory, The Salk Institute for Biological Studies, San Diego, California 92186, USA. kanemitsu@AXP1.salk.edu
Jiang
W
W
Eckhart
W
W
D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002460:Cell Line; D018031:Connexin 43 / Q000737:chemistry / Q000378:metabolism*; D019926:Cyclin B / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008938:Mitosis; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats
D018031:Connexin 43; D019926:Cyclin B; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; C082868:butyrolactone I; D016203:CDC2 Protein Kinase; D015107:4-Butyrolactone