Cloning, functional characterization, and mechanism of action of the B-cell-specific transcriptional coactivator OCA-B.
Biochemical purification and cognate cDNA cloning studies have revealed that the previously described transcriptional coactivator OCA-B consists of a 34- or 35-kDa polypeptide with sequence relationships to known coactivators that function by protein-protein interactions. Studies with a recombinant protein have proved that a single OCA-B polypeptide is the main determinant for B-cell-specific activation of immunoglobulin (Ig) promoters and provided additional insights into its mechanism of action. Recombinant OCA-B can function equally well with Oct-1 or Oct-2 on an Ig promoter, but while corresponding POU domains are sufficient for OCA-B interaction, and for octamer-mediated transcription of a histone H2B promoter, an additional Oct-1 or Oct-2 activation domain(s) is necessary for functional synergy with OCA-B. Further studies additional Oct-1 or Oct-2 activation domain(s) is necessary for functional synergy with OCA-B. Further studies show that Ig promoter activation by Oct-1 and OCA-B requires still other general (USA-derived) cofactors and also provide indirect evidence that distinct Oct-interacting cofactors regulate H2B transcription.
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Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, New York 10021, USA.
Roeder
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D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000502:physiology*; D002454:Cell Differentiation; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D006657:Histones / Q000096:biosynthesis; D051863:Host Cell Factor C1; D006801:Humans; D007136:Immunoglobulins / Q000096:biosynthesis* / Q000235:genetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014018:Tissue Distribution; D015534:Trans-Activators / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D006657:Histones; D051863:Host Cell Factor C1; D007136:Immunoglobulins; D050811:Octamer Transcription Factor-1; C091546:POU2AF1 protein, human; C494165:POU2F1 protein, human; D015534:Trans-Activators; D014157:Transcription Factors