Fig. 1.

Nab2 binds polyadenosine RNA with high affinity. (A) Representative normalized FCS curves from a binding titration experiment where a concentrated sample of Nab2 (2.5 μM) was serially diluted while the Cy3-poly(A)₂₅ RNA concentration (≈140 nM) remained constant. As Nab2 is diluted, the FCS decay curves shift to the left, indicating a decrease in the fraction of bound oligonucleotide. (B) FCS decay curves from A were used to determine the fraction of Nab2-bound Cy3-poly(A)₂₅ RNA. Data were fit with Eq. 1 (SI Methods) by using global fit analysis to yield a K_d of 29 ± 10 nM.