The ubiquitous octamer-binding protein Oct-1 contains a POU domain with a homeo box subdomain.
The octamer motif ATGCAAAT is recognized indistinguishably by two mammalian transcription factors: one that is expressed ubiquitously and referred to here as Oct-1, and another, Oct-2, that is expressed in lymphoid cells. We report the cDNA cloning of the human oct-1 gene, which encodes Oct-1, by screening lambda gt11 recombinant phage in situ for octamer motif-specific DNA binding. One lambda gt11 recombinant expressed a beta-galactosidase-octamer-binding fusion protein with a DNA-binding specificity indistinguishable from human HeLa cell Oct-1 protein. As expected for a ubiquitously expressed protein, Oct-1 mRNA is expressed in all five human and two mouse cell lines tested. Polyclonal rabbit antiserum raised against the beta-galactosidase fusion protein shows that the DNA-binding domains of Oct-1 and Oct-2 proteins are related antigenically. Deletion analysis of the 743-amino-acid-long oct-1 open reading frame shows that the DNA-binding activity lies within a central highly charged domain of 160 amino acids. Comparison of the Oct-1 and Oct-2 sequences reveals that this domain is nearly identical between the two proteins. Highly similar domains are also present in the pituitary-specific transcription factor Pit-1 and the Caenorhabditis elegans unc-86 cell lineage gene product (see Herr et al. 1988). Within this shared POU (Pit-1, Oct-1 and Oct-2, unc-86) domain (pronounced 'pow') lie two subdomains: a POU-related homeo box and a POU-specific box. The Oct-1 protein is unique among the POU-related proteins and other homeo box proteins because it is expressed ubiquitously.
Sturm
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Cold Spring Harbor Laboratory, New York 11724.
Das
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Herr
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D000595:Amino Acid Sequence; D000818:Animals; D010582:Bacteriophage lambda / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics*; D005796:Genes; D005801:Genes, Homeobox; D051863:Host Cell Factor C1; D006801:Humans; D015151:Immunoblotting; D008221:Lymphoid Tissue / Q000166:cytology; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D050811:Octamer Transcription Factor-1; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D015183:Restriction Mapping; D014157:Transcription Factors / Q000235:genetics; D001616:beta-Galactosidase / Q000235:genetics
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; C497693:Hcfc1 protein, mouse; D051863:Host Cell Factor C1; D009687:Nuclear Proteins; D050811:Octamer Transcription Factor-1; C494165:POU2F1 protein, human; C494166:Pou2f1 protein, mouse; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D001616:beta-Galactosidase