Enables guanyl-nucleotide exchange factor activity. Predicted to be involved in several processes, including G1/S transition of mitotic cell cycle; regulation of mitotic nuclear division; and spindle organization. Predicted to act upstream of or within cell division. Predicted to be located in chromatin and nucleus. Predicted to be part of protein-containing complex. Predicted to be active in cytoplasm. Is expressed in several structures, including alimentary system; central nervous system; metanephros; reproductive system; and vibrissa. Orthologous to human RCC1 (regulator of chromosome condensation 1). [provided by Alliance of Genome Resources, Apr 2022]