Regulation of Hemichannels and Gap Junction Channels by Cytokines in Antigen-Presenting Cells
Figure 1
Connexin 43 and pannexin1 at gene and protein levels. Left: a diagram depicting the genomic regions, mRNA, and membrane topology of human connexin 43 (Cx43, top left) and pannexin 1 (Panx1, bottom left). Genomic loci are represented by black boxes that stand for the corresponding exons. mRNA diagrams representing the exons as coding protein regions (red boxes) and 3′- and 5′-non-coding areas (purple boxes) are shown. The intron lengths are indicated in the schemes of genomic loci, and exon sizes are indicated in the mRNA diagrams. In the membrane topology the white squares indicate extracellular cysteine residues of each protein. Six protein subunits constitute a hemichannel (HC), which has different pore sizes. Right: two adjoining cells forming a gap junction channel (GJC) at the cell interface. Each cell presents HCs formed by Cx43 or Panx1. Arrows denote the bidirectional communication with the intracellular milieu (ICM) for GJCs and the extracellular milieu (ECM) for HCs; some immunorelevant molecules are shown. Dotted line for Ca2+ permeating Panx1 HCs indicates that this phenomenon is not fully demonstrated.
