Ribsomes
Secretory pathway (ER ribosomes)
Organellar Targeting (Free ribosomes)::
nuclear proteins, mitochondrial proteins, chloroplast proteins, peroxisomal proteins, some plasma mem proteins
protein residents of other organells are directly targeted to those organelles independent of secretory pathway functions
most translated on free ribosomes
may or may not fold in cytosol
post translationally targeted into organelle
Mitochondria
@@Mito Encoded::@@
@@Nuclear Encoded:@@:
Mito Import machinery::
Path A and B
Path C
@@Peroxisome::@@
@@nuclear encoded@@
post translationally imported into peroxisome
imported as folded proteins
two targeting seq, PTS1 and PTS2
Pex5 is receptor, binds to Pex14, transfers to Pex12/2, then Pex5 releases
@@Nucleus::@@
@@all proteins translated in cytosol@@
folded proteins transported
nuclear localization signal for nuclear proteins, near c term
nuclear pore complex- spans both bilayers, huge
nuclear import- occurs via diffusion
nuclear export- driven by Ran GTPase
Ran Independent nuclear import also exists
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