Some preparations of polymerase II show three different
forms of the largest subunit (RPB1). Give the names of
these subunits and show their relative positions after SDSPAGE. What are the differences among these subunits?
Present evidence for these conclusions.
Diagram the elution pattern of the eukaryotic nuclear RNA
polymerases from DEAE-Sephadex chromatography. Show
what you would expect if you assayed the same fractions in
the presence of 1 mg/mL of a-amanitin.
Draw a T–A base pair. Based on that structure, draw a line
diagram indicating the relative positions of the hydrogen bond
acceptor and donor groups in the major and minor grooves.
Represent the horizontal axis of the base pair by two segments
of a horizontal line, and the relative horizont
You have the following working hypothesis: To bind well to
a DNA-binding protein, a DNA target site must twist less
tightly and widen the narrow groove between base pairs 4
and 5. Suggest an experiment to test your hypothesis
An asparagine in a DNA-binding protein makes an important
hydrogen bond with a cytosine in the DNA. Changing this
glutamine to alanine prevents formation of this hydrogen
bond and blocks the DNA–protein interaction. Changing the
cytosine to thymine restores binding to the mutant protein.