Fish glucocorticoid receptor with splicing variants in the DNA binding domain.

Here we describe the isolation of a rainbow trout cDNA containing an entire GR coding region. Although the encoded protein is highly homologous to other GRs, especially in its DNA binding domain, it contains a nine amino acid insertion between the two zinc fingers. This novel form is found in all rainbow trout tissues examined; however, the testis also contains a splice variant lacking this insert, making it completely continuous to other GRs. In transient transfection assays of cultured cells, the two rainbow trout GR variants activated transcription from the glucocorticoid-responsive mouse mammary tumor virus promoter to comparable levels.