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Ch15 Intracellular Compartments and Protein Transport - Coggle Diagram
Ch15
Intracellular Compartments and Protein Transport
Origins
Invagination of plasma membrane
Endomembrane system
Golgi
Endosome
Lysosome
ER
Nuclear membr
precursors likely simple microorg: present archaea
Plasma memb
No organelles
endosymbiosis
aerobic bacterium engulfed by anaerobic euk
proteins
synth begin with ribosomes in cytosol
destination organelle directed by AA sequ that contains
sorting signal
physical properties and placement of charged AAs more important for function
not exact AA sequ
mechanisms of transport
transport across membranes
protein translocators
protein usually
needs to unfold
to be guided across hydrophobic interior of membrane
Signal sequence removed after
Mitochondria, chloroplasts
require protein import
require import of
new lipids
transport by vesicles
entering peroxisome
proteins do NOT require unfolding
enter rfom cytosol and ER
3 AA signal sequence
entering ER
water soluble
completely translocated
SRP and SRP receptor
prospective transmembrane proteins
partly translocated
stop-transfer sequences
N-terminal sig sequ
cleaved
start-transfer sequence
internal sig sequ
not removed
directed to enter ER by ER signal sequence
8 or more hydeophob AA
ribosomes:
free
membrane-bound
differ only in proteins they are making at any figen time
directed by ER signa; sequence to go to ER membrane
does NOT require more E to transport proteins out of ER
bind to mRNA- polyribosome
secrete proteins and other molecules via exocytosis
processes
budding
driven by protein coat assembly- "coated vesicle'
outward transport: need transport signal
recognized by cargo receptors of
golgi
plasma membrane
clathrin protein example
does NOT choose specific molecules for transport
Adaptins
secure clathrin coat
help select molecules for transport
COP-coated vesicles
transport btwn ER and Golgi
transport btwn parts of Golgi
docking
SNAREs
family of transmembrane proteins
also involved in catalyzing membrane fusion
require markers
Family of GTPases: "Rab proteins" on vesicle
need to be recogzd by corresponding tethering proteins
transport through nuclear pore
selective gates
enabled by unstructured regions in which polypept chains are largely disordered
work in both directions
rapidly
Need nuclear localization signal to get into nucleus (+AAs)
recognized by cytosolic proteins: "nuclear import receptors"
E from GTP hydrolysis
mediated by GTPase: "Ran"
Compartments
enclosed by membrane
double membrane:
nucleus
chloroplasts
mitochondria
Single membrane