DROSOPHILA-MELANOGASTER CONTAINS BOTH X-LINKED AND AUTOSOMAL HOMOLOGSOF THE GENE ENCODING CALCINEURIN-B

A transcription unit was identified in the 43E polytene band region of the second chromosome of Drosophila melanogaster (Dm) whose putative translation product has 85% amino acid (aa) identity with the B subuni t of the calcineurin protein (CnB) from humans. Unlike the previously described intronless Dm CnB gene homologue, which is located within th e 4F band region of the X chromosome, the coding region of this second CnB is found to be interrupted by three introns. Conceptual translati on of both Dm CnB genes predict proteins of identical size that are 98 % identical in aa sequence. Northern blot analyses indicate that Dm pu pae and adults express two different CnB-encoding transcripts that are differentially regulated.