BIOL 200 Lecture Notes - Lecture 33: Helicase, Polyadenylation, Intron
22 Jun 2016
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Document Summary
O gef phosphorylates ran; conformation change releases protein o ran-gtp binds to importin; importin concentration gradient causes complex to exit nucleus o gap hydrolyses ran-gtp to ran-gdp so it can bind to another protein. Protein export: ran and exportin dependent, trimeric complex formed within nucleus o ran-gtp, exportin, protein, complex goes through nuclear pore into cytoplasm, gap recognizes ran-gtp and hydrolyses it so components are released. Mature mrna associated with mrnp makes way to pore through activity of mrnp exporter. Immature mrnas are inhibited from exiting; phenomenon may be associated with activity of protein bound to a nucleoporins that actively blocks pre-mrna from leaving. Exporter interacts with hydrophobic domains and fg repeats. Mrna goes through npc in specific manner so that 5" end comes out first. As it reaches cytosol, rna helicase removes exporter, Sr proteins, and all other proteins bound to mrna. All removed molecules are recycled back to nucleus.
