Transcripts for functionally distinct isoforms of chicken GATA-5 are differentially expressed from alternative first exons.

Our analysis of cDNA and genomic clones unexpectedly revealed that the chicken gata-5 gene is differentially expressed from alternative first exons. Moreover, we show that the respective transcripts are differentially processed to yield mRNAs for two distinct isoforms of GATA-5. The major isoform, which we described previously, has two CXNCX17CNXC zinc fingers typical of a vertebrate GATA factor. The minor isoform, on the other hand, has only one such zinc finger. We show that this novel isoform localizes within the nuclei of transfected cells and can bind to a consensus GATA site. This truncated isoform of GATA-5 is compromised in its ability to transactivate a simple target gene, however, and thus is functionally distinct from the major isoform of GATA-5.