GJB4 Gene

The GJB4 gene (GJB4 is the acronym for gap junction protein beta 4) is a protein-coding gene located on chromosome 1p34.3.

The gene encodes a transmembrane connexin protein that is an essential component of gap junctions.

Mutations in this gene are associated with erythrokeratoderma variabilis

Non-syndromic hearing loss (Adadey SM et al. 2020).

An important paralog of this gene is GJB5.

In animal experiments, overexpression of GJB4 in primary pancreatic islet cells resulted in inhibition of islet cell proliferation and a decrease in insulin secretion.

Gap junctions belong to the system of cell contacts. Gap jun ctions (nexus, or macula communicans) consist of a collection ("plaques" or "cluster") of channels that lead through the cell membranes from cell to cell. Gap junctions thus directly connect the cytoplasm of adjacent cells. In this process, the membranes of the cells are fixed at a distance of only 2 to 4 nanometers from each other. Gap junctions, in contrast to tight junctions, leave a gap between them that can be seen under the electron microscope. The gap junction channels are formed by two hemichannels (connexons), of which each cell forms one half. Each connexon generally consists of 6 membrane-spanning proteins (in vertebrates, these are formed by the protein family of connexins - also membrane proteins). The connexins are arranged in a hexagonal pattern in such a way that a pore (gap) remains free in the middle.

1. Adadey SM et al (2020) GJB4 and GJC3 variants in non-syndromic hearing impairment in Ghana. Exp Biol Med (Maywood) 245:1355-1367.
2. de Oliveira RTG et al. (2020) Clinical variability of the GJB4:c.35G > A gene variant: a study of a large Brazilian erythrokeratodermia pedigree. Int J Dermatol 59:722-725.
3. Gässler A et al (2020) Overexpression of Gjb4 impairs cell proliferation and insulin secretion in primary islet cells. Mol Metab 41:101042.
4. James M et al (2018) A study on prevalence and risk factors of hearing impairment among newborns. Int J Contemp Pediatr 5:304-309.