Gap junction alpha-3 protein (Cx46) (IPR002262)

Short name: Connexin46

Overlapping homologous superfamilies

Family relationships

  • Connexin (IPR000500)
    • Gap junction alpha-3 protein (Cx46) (IPR002262)


Gap junction alpha-3 protein (also called connexin46, or Cx46) is a connexin of ~415 amino acid residues. The bovine form is slightly shorter (401 residues) and is hence known as Cx44, having a molecular mass of ~44 kD. Cx46 (together with Cx50) is a connexin isoform expressed in the lens fibres of the eye. Here, gap junctions join the cells into a functional syncytium, and also couple the fibres to the epithelial cells on the anterior surface of the lens. The lens fibres depend on this epithelium for their metabolic support, since they lose their intra-cellular organelles, and accumulate high concentrations of crystallins, in order to produce their optical transparency. Genetically-engineered mice deficient in Cx46 demonstrate the importance of Cx46 in forming lens fibre gap junctions; these mice develop normal lenses, but subsequently develop early onset senile-type cataracts that resemble human nuclear cataracts. Aberrant proteolysis of crystallin proteins was observed in the lenses of Cx46-null mice [PMID: 9413992]. A Cx46 mutant in a highly conserved threonine has been linked to autosomal dominant cataracts. This mutation causes loss of gap junction function and alters hemi-channel gating [PMID: 25404239].

GO terms

Biological Process

GO:0007154 cell communication
GO:0007601 visual perception

Molecular Function

GO:0005243 gap junction channel activity

Cellular Component

GO:0005921 gap junction

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.