A family of proteins (in the karyopherin superfamily) that are involved in regulating the export of proteins from the nucleus to the cytoplasm, the reverse of the task carried out by importins. Exportins bind to proteins with nuclear export signal sequences in association with ranGTP and pass into the cytoplasm through the nuclear pore complex. The protein cargo is released when the GTP is hydrolysed and the exportins diffuse back into the nucleus. Leptomycin B inhibits export by blocking the binding interaction of exportin with the nuclear export signal. Exportin-1 is CRM-1 (chromosome region maintenance-1, 1071 aa), exportin-6 (exp6, 1125 aa) seems to be specific for profilin-actin complexes and for maintaining the nucleus actin-free, exportin-T (962 aa) mediates the nuclear export of aminoacylated tRNAs.
Subjects: Medicine and Health — Chemistry.