The human lens intrinsic membrane protein MP70 (Cx50) gene: clonal analysis and chromosome mapping.

We have isolated and characterized a human genomic clone containing the complete coding region of lens intrinsic membrane protein MP70 (Cx50). The coding region of this DNA is completely contained within one exon, as is common of all connexins investigated to date. The size of the Cx50 coding region, from the initiating ATG to the terminating TGA is 1,299 nucleotides, coding for a polypeptide of 432 amino acids and having a translated molecular weight of 48,171 daltons. This Cx50 coding region DNA was used as a probe to analyze a panel of Southern blots of human-Chinese hamster somatic cell hybrid DNAs to assign the gene coding for Cx50 to its human chromosome. Control human and Chinese hamster DNAs displayed a distinct Eco R1 restriction fragment pattern when hybridized with the human Cx50 DNA probe. When somatic cell hybrid DNAs were restricted with Eco R1 and Southern blots hybridized with the human Cx50 DNA probe, the characteristic human restriction pattern was observed only when human chromosome 1 was present in the hybrid panel. Of the other six connexin genes which have previously been assigned to a human chromosome, two of these, Cx37 and Cx40, are also found on chromosome 1.