Crystallization and preliminary X-ray analysis of human RCC1, the regulator of chromosome condensation.

RCC1, the regulator of chromosome condensation, is the guanine nucleotide-exchange factor (GEF) of the GTP-binding protein Ran. Its GEF activity on Ran makes it a key element in nucleo-cytoplasmic transport and cell-cycle regulation. Crystals of human RCC1 suitable for X-ray analysis have been obtained using the seeding technique in hanging drops with sodium citrate as a precipitant. The crystals diffract to 1.7 A at 100 K and belong to the space group P1, with unit-cell parameters a = 49.5, b = 84.3, c = 84.9 A, alpha = 113.0, beta = 103.9,gamma = 103.3 degrees. The Matthews parameter (Vm) and the self-rotation function are consistent with three molecules in the unit cell, which is confirmed by the averaged single isomorphous replacement (SIR) electron-density map.