Gene structure and characterization of the murine homologue of the B cell-specific transcriptional coactivator OBF-1.
The B cell-specific activity of immunoglobulin (Ig) gene promoters is to a large extent mediated by the conserved octamer motif ATTTGCAT. This requires the DNA binding octamer factors Oct-1 and/or Oct-2, as well as an additional B cell-restricted non-DNA binding cofactor. We recently cloned such a coactivator specific for Oct-1 or Oct-2 from human B cells and called it OBF-1. Here we report the isolation and characterization of the murine homologue. Full-length cDNA clones as well as genomic clones were isolated and the gene structure was determined. The deduced protein sequence shows that the mouse protein has an identical length, is likewise proline rich and shows 89% overall identity to the human protein. The OBF-1 gene is expressed in a very highly B cell-specific manner and is transcribed in cells representative of all stages of B cell differentiation, including the earliest ones. We show that OBF-1 interacts in the absence of DNA with the POU domain of Oct-1 or Oct-2 and also with the general transcription factors TBP and TFIIB. Furthermore, we demonstrate that although OBF-1 efficiently activates promoter octamer sites, it does not activate enhancer octamer sites.
Schubart
D B
DB
Friedrich Miescher Institute, Basel, Switzerland.
Sauter
P
P
Massa
S
S
Friedl
E M
EM
Schwarzenbach
H
H
Matthias
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism; D001483:Base Sequence; D002454:Cell Differentiation; D004247:DNA / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000378:metabolism; D051863:Host Cell Factor C1; D006801:Humans; D007231:Infant, Newborn; D051379:Mice; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; D050809:POU Domain Factors; D011401:Promoter Regions, Genetic; D017385:Sequence Homology; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; C497693:Hcfc1 protein, mouse; D018398:Homeodomain Proteins; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; D050809:POU Domain Factors; C091546:POU2AF1 protein, human; C494165:POU2F1 protein, human; C058435:POU2F2 protein, human; C490424:Pou2af1 protein, mouse; C494166:Pou2f1 protein, mouse; C489206:Pou2f2 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D004247:DNA