IRES elements in connexin genes: a hypothesis explaining the need for connexins to be regulated at the translational level.

The fact that stem cells do not express gap junctions while most differentiated cells do suggests that gap junctions serve a vital function in the maintenance of the differentiated state. This would require that connexin genes be expressed even in conditions where cap-mediated translation is impaired. It is hypothesized that IRES elements in the 5'-UTRs of the mRNAs of most connexins are required for this purpose.