MCB 2050 Lecture Notes - Lecture 3: Y Chromosome, Hydrolysis, Nuclear Export Signal

• School: University of Guelph
• Department: Molecular and Cellular Biology
• Course: MCB 2050
• Professor: Peter Krell

Document Summary

Cytosol nuclear transport requires: energy, specific protein receptors, unique targeting signals. Nuclear imported proteins carry nls (nuclear localization signal: specific sequence of amino acids recognized by a protein receptor, both necessary and sufficient: wont get in without it, but it"s all you need! Classic nls: short stretch of basic (+ive) amino acids (kkqrkk) Karyopherins: importins (into nucleus) and exportins (out of nucleus, mobile proteins responsible for moving cargo across the nuclear envelope, require g-proteins which serve as molecular switches in the transport process (ran, rely on gap to convert/hydrolyze. In cytoplasm, importin recognizes and binds nls on nascent protein. Complex moves thru cytosol nucleus via cytoskeleton; importin binds to cytoplasmic filament on npc. Complex moves through channel on npc (not well understood) Importin binds ran-gtp resulting in its release from npc and disassembly. More ran-gtp in nucleus, more ran-gdp in cytosol (concentration gradient) Gtp hydrolysis provides energy for nucleo/cyto transport.