BIOB11H3 Lecture Notes - Lecture 8: Ribosome, Chromatin, Nucleoplasm
Document Summary
Proteins include structural proteins such as histones & proteins involved in dna metabolism. Provide structural support for nuclear envelope; anchors chromatin. *cell has 107 ribosomes, must import ~560,000 ribosomal proteins and export 14,000 ribosomal subunits every minute (cid:1) (cid:2) : enzymes associated with dna replication & transcription. Small proteins can freely diffuse into the nucleus. One to several different regions of a protein that contain short stretches of positively charges amino acids. Nls interacts with receptors that assist in transport to nucleus. Proteins with nls bind to heterodimic receptor (importin / ) Formation of complex that associates with cytoplasmic lament. Receptor-cargo complex moves through the nuclear pore into nucleoplasm. Ran-gdp & importin is transported back to the cytoplasm, where ran-gtp is hydrolyzed. Importins: soluble heterodimers which bind to nls-containing proteins. Exportins: guide proteins/rnas (nucleus to cytoplasm) by interaction w/ nuclear export signals. Both importins & exportins encoded by gene families.
