nuclear export first begins with the binding of ran-gtp (a g-protein) to exportin. this causes a shape change in exportin, increasing its affinity for the export cargo. once the cargo is bound, the ran-exportin-cargo complex moves out of the nucleus through the nuclear pore. gtpase activating proteins (gaps) then hydrolyze the ran-gtp to ran-gdp, and this causes a shape change and subsequent exportin release. once no longer bound to ran, the exportin molecule loses affinity for the nuclear cargo as well, and the complex falls apart. exportin and ran-gdp are recycled to the nucleus separately, and guanine exchange factor (gef) in the nucleus switches the gdp for gtp on ran.