Molecular cloning and developmental regulation of Dictyostelium discoideum homologues of the human and yeast HIV1 Tat-binding protein.

TBP1 and 7, two human cDNA clones, are members of a large, highly conserved family that encode proteins that bind to type 1 human immunodeficiency virus Tat protein, and may be transcription factors. Two Dictyostelium discoideum homologues, denoted DdTBP2 and 10, were isolated and characterized, and these have striking sequence similarity with both the human and yeast counterparts of the family. RNA blot analysis indicates that both DdTBP2 and 10 are developmentally regulated. Transcripts representing these cDNAs are highest in vegetatively growing cells, and their levels fall steadily throughout multicellular development and are not found in dormant or germinating spores. If indeed these proteins in Dictyostelium are also transcription factors, then this finding might indicate that only certain developmentally regulated genes require them.