TBP is a relatively small protein (~35kDa) that can bind DNA sequences (the TATA box) on its own with relatively high affinity. However if nuclear extracts are subjected to Gel Filtration Chromatography or Zonal Centrifugation and each eluted/collected fraction is tested in a western blot it appears that TBP is consistently found at a position that corresponds to approximately 500kDa. This fraction is still competent to drive transcription in vitro using a core promoter. Why might TBP behave like such a large protein?
Question 4 options:
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TBP exists in a large transcriptionally-competent multi-subunit complex |
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it can dimerize so its molecular weight would appear greater than predicted from its sequence |
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There may be other TBP like sequences that are recognised by the antibody |
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A and B |
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none of the abov |
