THE NUCLEOTIDE-SEQUENCE, STRUCTURE, AND PRELIMINARY STUDIES ON THE TRANSCRIPTIONAL REGULATION OF THE BOVINE ALPHA-SKELETAL-ACTIN GENE

The promoters of mammalian striated muscle actin genes contain binding sites for a number of transcription factors. Examples are the CArG boxes, which bind a protein identical to or related to serum response factor (SRF), E boxes, which bind myogenic determination factors such as MyoD and myogenin, and -CCGCCC-moths, which bind the transcription factor Sp1. To date, the only mammalian sequences isolated and analyzed are from rodent and human. We have now isolated and sequenced the bovine gene encoding a skeletal actin, including almost 3 kb of 5'-flanking region. When compared to the human and rodent genes (the only ones previously cloned and for which 5'-flanking sequences to only approximately -750 are known), there was the expected conservation in the coding region. A comparison of the promoter regions indicated that the bovine gene has three CArG boxes in the 5'-flanking region in positions identical to those in other species. The bovine proximal promoter is unique from those of human and rodent in that it has only one E box in the vicinity of the TATA box, near -350, whereas the other mammals have three. Far upstream sequences reveal clusters of E boxes near -2,500 and -1,500. A minimal promoter element, to -297, which has no E boxes, is sufficient to activate transcription in myotubes derived from rat L6 and mouse C2C12 myoblasts.