BIOL 1111 Lecture Notes - Nuclear Membrane, Cajal Body, Nucleolus Organizer Region
1 Feb 2013
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Lamin filaments peripheral nuclear lamina just inside nucleus. 2 types a/b intermediate filaments; dimerize as coiled coil dimmers will polymerize functions: mechanical strength chromatin attachment to envelope pore complex anchor/organizers nuclear shape. **lamins are v. important many laminopathies when mutated** Membrane proteins made in er and diffuse all the way to nuclear membrane. Import: requires exposed nls: important for nuclear entry (can get gold particle in w. right seq. ) requires energy. Rna"s bind to export proteins that have nes. Importin b binds importin a and mediates movement: importin binds cargo, nuclear import, ran-gtp binds importin cargo released, importin:ran-gtp exported, gtp hydrolysis importin released. **essential regulator of transport*: exportin binds cargo + ran-gtp, export, gtp hydrolysis disassembly, exportin is imported into nucleus. Chromatin euchromatin light in em heterochromatin darker constitutive: never expressed in any cell type (lacks genes) facultative: never expressed in certain cells (differentiated cells) Nucleosomes (beads on string) 30 nm fibers 80 nm fibers euch. heteroch.
