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Membrane Transport
Eukaryotes
Nuclear Import/Export
Ran-GTPase-driven transport of macromolecules through nuclear pore complexes.
Overview
Nuclear transport of proteins and RNAs occurs through nuclear pore complexes (NPCs), large structures composed of ~30 nucleoporin proteins. Import receptors (importins) recognize nuclear localization signals (NLS) on cargo and translocate through the NPC. The Ran-GTPase gradient (RanGTP in nucleus, RanGDP in cytoplasm) provides directionality. Exportins recognize nuclear export signals (NES) and transport cargo outward.
Cellular Location
Nuclear pore complex
Clinical Significance
Essential for gene expression regulation; viruses hijack nuclear import; CRM1 inhibitors (selinexor) approved for multiple myeloma; mutations in nucleoporins cause disease.