Guanine-nucleotide releasing factor that promotes the exchange of Ran-bound GDP by GTP, and thereby plays an important role in RAN-mediated functions in nuclear import and mitosis. Contributes to the generation of high levels of chromosome-associated, GTP-bound RAN, which is important for mitotic spindle assembly and normal progress through mitosis. Via its role in maintaining high levels of GTP-bound RAN in the nucleus, contributes to the release of cargo proteins from importins after nuclear import. Involved in the regulation of onset of chromosome condensation in the S phase. Binds both to the nucleosomes and double-stranded DNA. Interacts with RAN. Interacts (via N-terminus and RCC1 repeats) with KPNA4. Interacts with ARRB2; the interaction is detected in the nucleus upon OR1D2 stimulation. Predominantly nuclear in interphase cells. Binds to mitotic chromosomes. N-terminal methylation by METTL11A/NTM1 is required for binding double-stranded DNA and stable chromatin association. Dimethylation produces a permanent positive charge on the amino group, which facilitates electrostatic binding to the phosphate groups on DNA, while inhibiting histone-binding. Methylated tail helps retain RCC1 on chromosomes during nucleotide exchange on Ran.