OBF-1, a novel B cell-specific coactivator that stimulates immunoglobulin promoter activity through association with octamer-binding proteins.
Recent biochemical and genetic studies indicate that in addition to the octamer-binding proteins Oct-1 and Oct-2, other B cell components are required for lymphoid-restricted, octamer site-mediated immunoglobulin gene promoter activity. Using a genetic screen in yeast, we have isolated B cell-derived cDNAs encoding Oct-binding factor 1 (OBF-1), a novel protein that specifically associates with Oct-1 and Oct-2. Biochemical studies demonstrate that OBF-1 has no intrinsic DNA-binding activity and recognizes the POU domains of Oct-1 and Oct-2, but not those of Oct-4 and Oct-6. The OBF-1 mRNA is expressed in a highly cell-specific manner, being most abundant in B cells and essentially absent in most of the other cells or tissues tested. Furthermore, expression of OBF-1 in HeLa cells selectively stimulates the activity of a natural immunoglobulin promoter in an octamer site-dependent manner. Thus, OBF-1 has all the properties expected for a B cell-specific transcriptional coactivator protein.
Strubin
M
M
Department of Genetics and Microbiology, University Medical Centre, Geneva, Switzerland.
Newell
J W
JW
Matthias
P
P
D000595:Amino Acid Sequence; D001402:B-Lymphocytes; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D015723:Gene Library; D005803:Genes, Immunoglobulin / Q000235:genetics*; D006367:HeLa Cells; D051863:Host Cell Factor C1; D006801:Humans; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; D009928:Organ Specificity; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012331:RNA, Fungal / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D017422:Sequence Analysis, DNA; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics*; D015003:Yeasts / Q000235:genetics
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; C091546:POU2AF1 protein, human; C494165:POU2F1 protein, human; C058435:POU2F2 protein, human; D012331:RNA, Fungal; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D004247:DNA