CRM1 (Exportin-10) [C1]

Protein transport across the nucleus is a selective, multistep process involving several cytoplasmic factors. Proteins must be recognized as import substrates, dock at the nuclear pore complex and translocate across the nuclear envelope in an ATP-dependent fashion. Chromosome region maintenance 1 (CRM1), also known as Exportin-1, is a protein essential for nuclear export of hundreds of proteins, mRNAs, and rRNAs. CRM1 has been shown to be an export receptor for leucine-rich proteins that contain the nuclear export signal (NES). These hydrophobic sequences form an alpha-helix-loop that can bind to the exportin-1 hydrophobic groove. Studies have shown that these NESs can be modified either by protein modifications or by mutation to regulate exportin-1 binding. Targets of CRM1 include many tumor suppressors, such as Rb, p53, FoxO1, BAF47, as well as oncoproteins, such as p21 and p27.