Analysis of the proximal transcriptional element of the myelin basic protein gene.

The gene encoding myelin basic protein (MBP) contains multiple activator sequences spanning upstream of its transcriptional initiation site which differentially promote transcription in glial cells. The proximal activator sequence, designated MB1, activates transcription in a glial cell type specific manner. This sequence resides between -14 to -50 with respect to the RNA initiation site of the MBP gene. We have identified within the MB1 sequence a 10-nucleotide domain, 5'-ACCTTCAAAG-3', that increases transcription of a test promoter in glial and Schwann cells. This proximal motif functions in both orientations and specifically interacts with a nuclear protein derived from glial cells. Results of in vivo competition experiments indicate that this 10-nucleotide motif positively contributes to the overall transcriptional activity obtained from the entire MBP promoter in glial cells.