HUMAN A-MYB GENE ENCODES A TRANSCRIPTIONAL ACTIVATOR CONTAINING THE NEGATIVE REGULATORY DOMAINS

The myb gene family has three members, c-myb, A-myb, and B-myb. A-myb mRNA is mainly expressed in testis and peripheral blood leukocytes. A- Myb can activate transcription from the promoter containing Myb-bindin g sites in all cells examined. In addition to the two domains (a DNA-b inding domain and a transcriptional activation domain), two negative r egulatory domains have been identified in A-Myb. These results indicat e that A-Myb functions as a transcriptional activator mainly in testis and peripheral blood cells, and the regulatory mechanism of A-Myb act ivity is similar to that of c-Myb.