Fig. 1.
Current in vitro measurements are inconsistent with nucleocytoplasmic transport. Relationship between Kd and half-life of a binary complex (red line). Physiological on-rates for protein-protein interactions usually range from 104 to 106 m−1 s−1 (gray lines flanking red line). However, the measurements of Kd between Kaps and FG nups typically fall in the low nanomolar range, giving a range half-lives (purple region) that are inconsistent with half-lives expected for known transport rates of ∼30 ms (green region).