Importins and Exportins Regulating Allergic Immune Responses

Figure 1

Nucleocytoplasmic transport of macromolecules via importin-exportin pathway. In the cytoplasm, importin-α forms a heterotrimeric complex with importin-β1, RanGDP, and NLS containing cargo protein. This heterotrimeric complex passes through the NPC into the nucleus and RanGTP binds to importin-β1 and disassembles the complex in the nucleus. The binding of exportin to NES within the cargo protein is triggered by RanGTP in the nucleus and is exported back to the cytoplasm through nuclear pore complex (NPC). In the cytoplasm, the dissociation of the complex is mediated through the hydrolysis of RanGTP to RanGDP by GAP (GTPase activating protein) that forces the binding of GDP to Ran. GEF (guanine nucleotide exchange factor) is a nucleoplasmic factor that stimulates exchange of GDP with GTP forming RanGTP in the nucleus.