Splice variants of the condensin II gene Ncaph2 include alternative reading frame translations of exon 1.

Condensins I and II are five-protein complexes that are important for the condensation of chromatin. They are essential for mitosis and important for regulating gene expression during interphase. Here, we investigated the transcription and translation of the mouse Ncaph2 gene, which encodes a subunit of condensin II. We identified three splice variants within the first exon, a NAGNAG splice variant at the beginning of exon 16 and alternative 3'-UTRs. In total, Ncaph2 is potentially capable of generating 12 unique mRNA transcripts and six unique proteins. We confirm that Ncaph2 can generate three different N-termini, all encoded by exon 1, one of which is translated from an alternative reading frame. This alternative reading frame splice variant appears to be a novel outcome of splicing. If this is applicable to other genes, it would account for a previously unappreciated level of eukaryotic protein diversity.