A B-cell coactivator of octamer-binding transcription factors.
The octamer motif (ATGCAAAT) paradoxically plays a central role in mediating the activity of both B-cell specific and ubiquitous promoters. It has been widely assumed that the predominantly lymphoid-restricted octamer-binding factor Oct-2 mediates tissue-specific promoter activity, whereas the ubiquitously expressed Oct-1 mediates general promoter activity, but this view has been challenged. Here we use a modified yeast one-hybrid assay to isolate a B-cell factor, Bob1, which associates with either Oct-2 or Oct-1. In transfection experiments, this factor boosts Oct-1-mediated promoter activity and to a lesser extent, that of Oct-2. This coactivation is strictly dependent on the specific interaction with Oct-1 or Oct-2 because deletion of the octamer motif abolishes coactivation. We conclude that Bob1 could represent a new tissue-specific transcriptional coactivator which may convert a ubiquitously expressed transcription factor to a cell-type-specific activator.
Gstaiger
M
M
Institut für Molekularbiologie II der Universität Zürich, Switzerland.
Knoepfel
L
L
Georgiev
O
O
Schaffner
W
W
Hovens
C M
CM
D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D051863:Host Cell Factor C1; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000235:genetics; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D007145:Immunoglobulin kappa-Chains; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; C091546:POU2AF1 protein, human; C494165:POU2F1 protein, human; C058435:POU2F2 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D004247:DNA