Endoplasmic Reticulium Flashcards
Why are proteins important?
Bioactive molecules of the cell
Catalyse multiple enzymatic reaction
Function of proteins dictated by structural conformation
Proteins play a role in cytoskeleton
Actin & tubulin
What does protein shape dictate?
Enzyme activity
What do proteins form?
The basis of signalling cascades to activate cellular adaption and responses
What is the role of the ER?
Smooth ER
lipid/steroid synthesis
Drug detoxification
Drugs induce ER proliferation
Rich Ca2+ store
In animal cells, increases in Ca2+ may cause;
1) contraction of muscle cells
2) secretion of certain substances
3) cell division
Why can Ca2+ function as a second messenger?
It’s concentration in the cytoplasm is normally much lower than the concentration outside the cell
Cells use Ca2+ as a second messenger in both the;
- G-protein pathways
- tyrosine-kinase pathways
What is the role of the ER? Rough
Ribosome rich - polypeptide synthesis
folding of the polypeptide chain to active conformation
Membrane protein synthesis
Folded proteins trafficked to Golgi via transport vesicles
How do newly synthesised peptides get from the ribosome to the ER lumen?
mRNA processed through ribosome complex to produce polypeptide chain
ER signal sequence directs ribosome translocator to ER membrane
Misfolded proteins in the ER lumen are recognised and targeted to a…
Translocator complex in the ER membrane
What do signals to the nucleus’s in misfolded protein activate the UPR?
Upregulated and array of regulatory and cell survival processes
Describe the UPR in disease;
Long-term activation of the UPR is associated with pathogenic dysfunction and disease
Brings about a state of ER stress
Common feature in protein misfolding and accumulation disorders
How are ER and mitochondria physically linked?
Tethered together via the mitochondrial associated membranes
How does ER-mitochondria contract couple mtDNA synthesis?
With downstream mitochondrial division events to distribute newly replicated mtDNA to daughter mitochondria
