The POU-specific domain of Pit-1 is essential for sequence-specific, high affinity DNA binding and DNA-dependent Pit-1-Pit-1 interactions.
Pit-1 is a member of a family of transcription factors sharing two regions of homology: a highly conserved POU-specific (POUS) domain and a more divergent homeodomain (POUHD). Analysis of mutant Pit-1 proteins suggests that, while the POUHD is required and sufficient for low affinity DNA binding, the POUS domain is necessary for high affinity binding and accurate recognition of natural Pit-1 response elements. Pit-1 is monomeric in solution but associates as a dimer on its DNA response element, exhibiting DNA-dependent protein-protein interactions requiring the POUS domain. Analysis of alpha-helical domains and conserved structures in Pit-1 suggests that POU domain proteins interact with their DNA recognition sites differently than classic homeodomain proteins, with both the POUHD and the POUS domain contacting DNA. Transcriptional activity of Pit-1 on enhancer elements is conferred primarily by a Ser- and Thr-rich N-terminal region unrelated to other known transcription-activating motifs.
Ingraham
H A
HA
Howard Hughes Medical Institute, School of Medicine, University of California, San Diego, La Jolla 92093.
Flynn
S E
SE
Voss
J W
JW
Albert
V R
VR
Kapiloff
M S
MS
Wilson
L
L
Rosenfeld
M G
MG
D000465:Algorithms; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D009838:Oligodeoxyribonucleotides / Q000378:metabolism*; D015345:Oligonucleotide Probes / Q000138:chemical synthesis; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D011487:Protein Conformation; D015183:Restriction Mapping; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection
D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D015345:Oligonucleotide Probes; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D004247:DNA