Distribution of genes for gap junction membrane channel proteins on human and mouse chromosomes

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Abstract
Gap junctions are widely distributed structures that mediate communication between cells. The channels that allow passage of small molecules between adjacent cells are made up of oligomeric proteins (connexins) that are encoded by a family of related genes. By probing somatic cell hybrid DNA on Southern filters with rat or human cDNAs or human genomic fragments, we have mapped four functioning gap junction genes, (α1, β1, β2, and α3), to different sites on human chromosomes:GJA1 (connexin43) to 6p21.1–q24.1;GJB1 (connexin32) to Xcen-q22;GJB2 (connexin26) to 13; andGJA3 (connexin46) also to 13, probably nearGJB2. The GJA3 probe also hybridized to a restriction fragment that was mapped to chromosome 1. A GJA1-related pseudogeneGJA1P was assigned to chromosome 5. The homologous loci in mouse were assigned to regions of known conserved syntenic groups:Gja-1 to chromosome 10;Gjb-1 to XD-F4 andGjb-2 to 14. Of two sites of hybridization with the GJA3 probe, on mouse 14 and 5, we assume that the site on 14 corresponds to theGJA3 locus on human 13. Based on these data, additional members of this family of related genes can be isolated and characterized, and possible human and mouse mutations can be identified.