Octamer transcription factors 1 and 2 each bind to two different functional elements in the immunoglobulin heavy-chain promoter.
Immunoglobulin heavy-chain genes contain two conserved sequence elements 5' to the site of transcription initiation: the octamer ATGCAAAT and the heptamer CTCATGA. Both of these elements are required for normal cell-specific promoter function. The present study demonstrates that both the ubiquitous and lymphoid-cell-specific octamer transcription factors (OTF-1 and OTF-2, respectively) interact specifically with each of the two conserved sequence elements, forming either homo- or heterodimeric complexes. This was surprising, since the heptamer and octamer sequence motifs bear no obvious similarity to each other. Binding of either factor to the octamer element occurred independently. However, OTF interaction with the heptamer sequence appeared to require the presence of an intact octamer motif and occurred with a spacing of either 2 or 14 base pairs between the two elements, suggesting coordinate binding resulting from protein-protein interactions. The degeneracy in sequences recognized by the OTFs may be important in widening the range over which gene expression can be modulated and in establishing cell type specificity.
Poellinger
L
L
Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, New York 10021.
Roeder
R G
RG
D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005803:Genes, Immunoglobulin; D006367:HeLa Cells / Q000378:metabolism; D051863:Host Cell Factor C1; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; C494165:POU2F1 protein, human; C058435:POU2F2 protein, human; D014157:Transcription Factors; D004247:DNA