THE MOUSE GENE CODING FOR HIGH-MOBILITY GROUP-1 PROTEIN (HMG1)

We have isolated an active gene encoding the mouse HMG1 protein among a multitude of cross-hybridizing sequences, which most likely are retrotransposed pseudogenes. The hmg1 gene contains five exons, of which the first is not translated, and the last contains a long 3'-untranslated sequence and three alternative polyadenylation sites. We found no evidence for a sequence encoding a membrane localization signal in the hmg1 gene, despite the presence of HMG1 protein on the surface of several cell types. The hmg1 promoter coincides with a CpG island, contains no TATA sequence, and drives the expression of reporter genes placed under its control. The hmg1 gene may be a member of a family of closely related genes but appears to be the major or the only active gene coding for HMG1 protein.