Homologous Superfamily

Gap junction alpha-1 protein (Cx43), alpha helix domain superfamily (IPR035091)

Short name: Alpha_helix_dom_sf

Overlapping entries


Gap junction alpha-1 protein (also called connexin43, or Cx43) is a connexin of 381 amino acid residues (human isoform) that is widely expressed in several organs and cell types, and is the principal gap junction protein of the heart. Characterisation of genetically-engineered mice that lack Cx43, and also of human patients that have spontaneously-occurring mutations in the gene encoding it (GJA1), suggest Cx43 is essential for the development of normal cardiac architecture and ventricular conduction. Mice lacking Cx43 survive to term but die shortly after birth. They have cardiac malformations that lead to the obstruction of the pulmonary artery, leading to neonatal cyanosis, and subsequent death. This phenotype is reminiscent of some forms of stenosis of the pulmonary artery. Human subjects with visceroatrial heterotaxia (a heart disorder characterised by arterial defects), have been found to have points mutations in the Cx43-encoding gene, as a result of which a potential phosphorylation site within the C terminus is disrupted. Consequently, although these mutant Cx43 molecules still form functional gap junction channels, their response to protein kinase activation is impaired.

Regulation of cell-cell communication by the gap junction protein connexin43 can be modulated by a variety of connexin-associating proteins. In particular, c-Src can disrupt the connexin43 (Cx43)-zonula occludens-1 (ZO-1) interaction, leading to down-regulation of gap junction intercellular communication.

The connexin43 carboxyl-terminal domain (Cx43CT) exists primarily as an elongated random coil, with two regions of alpha-helical structure. The alpha-helical domains has two hypothetical roles. The first one is to allow the formation of a higher order structure necessary to regulate channel behavior during chemical gating and the second is to act as a conduit for a cross-talk between different Cx43 binding partners [PMID: 15492000].

Contributing signatures

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