Murine collagen intron-binding factor I (CIBF-I) is the same protein as transcription factor Oct-1.
The recognition sequence (CIB) of collagen intron-binding factor I (CIBF-I) loosely resembles the consensus octamer-binding motif (OCT). In the present study we investigate whether CIBF-I is actually the OCT-binding protein, Oct-1. Electrophoretic mobility-shift assays (EMSA) demonstrate that a consensus OCT motif effectively competes for CIBF-I binding. CIBF-I and Oct-1 complexes display similar EMSA characteristics, and both factors are detected in nuclear extracts of five different cell types. In addition, pre-incubation of nuclear extracts with antiserum directed against the POU domain of Oct-1 inhibits CIBF-I complex formation. Finally, DNA transfection experiments demonstrate that a single copy of the CIB site is sufficient to stimulate transcription from the SV40 early promoter in NIH 3T3 cells. These results suggest that CIBF-I is the ubiquitously distributed OCT-binding protein, Oct-1, and represent the first report that an octamer-binding protein contributes to the transcriptional activity of a collagen-encoding gene.
Pogulis
R J
RJ
Molecular Biology Research Program, Case Western Reserve University, Henry Ford Health Sciences Center, Detroit, MI 48202, USA.
Geddes
T J
TJ
Freytag
S O
SO
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D003094:Collagen / Q000096:biosynthesis / Q000235:genetics*; D016384:Consensus Sequence; D003429:Cross Reactions; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D005786:Gene Expression Regulation; D051863:Host Cell Factor C1; D051379:Mice; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D011485:Protein Binding; D014157:Transcription Factors / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; C497693:Hcfc1 protein, mouse; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; C494166:Pou2f1 protein, mouse; D014157:Transcription Factors; D003094:Collagen