FIGURE 3.

DNA binding by CTD constructs. Binding of a fluorescein-tagged, double-stranded 37-mer oligonucleotide (20 nm), monitored as a function of CTD concentration by fluorescence anisotropy, was determined. The apparent K_d values are as follows: tail-less 90 nm ± 21 nm; insert-less, 42 nm ± 8 nm; full-length, not determined.