Change in permeant size selectivity by phosphorylation of connexin 43 gap-junctional hemichannels by PKC.
Gap-junctional channels, permeable to large hydrophilic solutes of up to M(r) approximately 1,000, are responsible for cell-to-cell communication. Phosphorylation of connexin 43 (Cx43) by PKC abolishes the permeability of gap-junctional channels and hemichannels to large hydrophilic solutes, but not to small inorganic ions. Here, we report on a methodology to produce purified hemichannels of controlled subunit composition and apply it to the generation of hemichannels with variable number of PKC-phosphorylated subunits. The subunit composition was determined by luminescence resonance energy transfer. We show that all Cx43 subunits in the hemichannel hexamer have to be phosphorylated to abolish sucrose (M(r) 342) permeability. We also show that the hemichannel pores with all subunits phosphorylated by PKC have a sizable diameter, allowing for permeation of the small hydrophilic solute ethyleneglycol (M(r) 62). These results indicate that phosphorylation of Cx43 by PKC alters the hemichannel size selectivity and explain why PKC activity affects dye transfer between cells without consistent effects on electrical communication.
Bao
Xiaoyong
X
Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555-0437, USA.
Lee
Sung Chang
SC
Reuss
Luis
L
Altenberg
Guillermo A
GA
D002850:Chromatography, Gel; D018031:Connexin 43 / Q000378:metabolism*; D004735:Energy Transfer; D017629:Gap Junctions / Q000378:metabolism*; D010316:Particle Size; D010539:Permeability; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D012995:Solubility; D013395:Sucrose / Q000378:metabolism; D013725:Terbium / Q000378:metabolism
D018031:Connexin 43; D021122:Protein Subunits; D013725:Terbium; D013395:Sucrose; D011493:Protein Kinase C