 Importins release cargo upon binding to RanGTP, while exportins must bind RanGTP to form a ternary complex with their export cargo.The dominant nucleotide binding state of Ran depends on whether it is located in the nucleus (RanGTP) or the cytoplasm (RanGDP).Importin proteins bind their cargo in the cytoplasm, after which they are able to interact with the nuclear pore complex and pass through its channel.