Characterization of a human homologue of the Saccharomyces cerevisiae transcription factor spt3 (SUPT3H).

Spt3 is a Saccharomyces cerevisiae transcription factor that is required in vivo for the transcription of a number of RNA polymerase II-transcribed genes. We report the cloning of the gene encoding the human homologue of Spt3, SUPT3H, and its initial functional analysis. The human and yeast Spt3 homologues share an overall identity of 30% that defines three conserved regions, suggesting possible functional domains. To determine whether SUPT3H is a true functional Spt3 homologue, we tested for complementation of an spt3Delta mutation in yeast. While expression of the full-length SUPT3H is unable to complement an spt3Delta mutation, expression of a human-yeast chimeric gene that contains 42% human sequences can partially complement an spt3Delta mutation. These data suggest that the transcriptional control carried out by Spt3 has been conserved from yeast to human.