Chromatin-associated RCC1 mediates GDP to GTP exchange on RAN, resulting in formation of the active RAN:GTP complex (Hetzer et al. 2000, reviewed by Zierhut and Funabiki 2015). The high concentration of RAN:GTP near chromatin promotes multiple aspects of nuclear envelope reassembly (reviewed by Forbes et al. 2015). RAN:GDP may be involved in recruitment of RCC1 to chromatin (Zhang et al. 2002).