Cx50 requires an intact PDZ-binding motif and ZO-1 for the formation of functional intercellular channels

Mol Biol Cell. 2011 Dec;22(23):4503-12. doi: 10.1091/mbc.E11-05-0438. Epub 2011 Sep 30.


The three connexins expressed in the ocular lens each contain PDZ domain-binding motifs directing a physical association with the scaffolding protein ZO-1, but the significance of the interaction is unknown. We found that Cx50 with PDZ-binding motif mutations did not form gap junction plaques or induce cell-cell communication in HeLa cells, whereas the addition of a seven-amino acid PDZ-binding motif restored normal function to Cx50 lacking its entire C-terminal cytoplasmic domain. C-Terminal deletion had a similar although weaker effect on Cx46 but little if any effect on targeting and function of Cx43. Furthermore, small interfering RNA knockdown of ZO-1 completely inhibited the formation of gap junctions by wild-type Cx50 in HeLa cells. Thus both a PDZ-binding motif and ZO-1 are necessary for Cx50 intercellular channel formation in HeLa cells. Knock-in mice expressing Cx50 with a PDZ-binding motif mutation phenocopied Cx50 knockouts. Furthermore, differentiating lens fibers in the knock-in displayed extensive intracellular Cx50, whereas plaques in mature fibers contained only Cx46. Thus normal Cx50 function in vivo also requires an intact PDZ domain-binding motif. This is the first demonstration of a connexin-specific requirement for a connexin-interacting protein in gap junction assembly.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Binding Sites
  • Cell Communication / genetics
  • Connexins / genetics
  • Connexins / metabolism*
  • Eye Proteins / genetics
  • Eye Proteins / metabolism*
  • Gap Junctions / metabolism*
  • Gene Knockout Techniques
  • HeLa Cells
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mutation
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Protein Structure, Tertiary
  • RNA, Small Interfering
  • Zonula Occludens-1 Protein


  • Connexins
  • Eye Proteins
  • Membrane Proteins
  • Phosphoproteins
  • RNA, Small Interfering
  • TJP1 protein, human
  • Tjp1 protein, mouse
  • Zonula Occludens-1 Protein
  • connexin 46
  • connexin 50