Lecture 8 - Protein Life Cycle Flashcards
When does protein folding begin to occur?
When proteins are being synthesized on the ribosome.
The function of a molecular chaperone is to:
reduce or prevent protein aggregation
Where do proteasomes exist?
cytoplasm
What is found in the 19S cap of the proteasome?
20 distinct proteins - 6 of which are ATPases
In protein ubiquitylation, what is the function of E1?
Ubiquitin-Activating Enzyme
In protein ubiquitylation, what is the function of E2?
Ubiquitin-Conjugating Enzyme
In protein ubiquitylation, what is the function of E3?
Ubiquitin Ligase
The signal sequence required for protein engagement with ER transport machinery is recognized by what?
Signal recognition particle or SRP - a multi-subunit RNA-protein particle that is a soluble, cytoplasmic protein emerging from the ribosome and leading to an arrest in protein translation.
Glycosylation is:
the covalent attachment of sugar molecules to proteins
What is responsible for transmembrane insertion of ER proteins?
Hydrophobic start and stop transfer sequences
Which disease is caused by a homozygous recessive mutation in the beta-globin gene?
Sickle cell anemia
Which disease is caused by an expansion of a CAG trinucleotide repeat in the htt gene?
Huntington’s disease
One type of protein aggregate that is particularly common in neurodegenerative diseases is the:
cross-beta filament
The most common mutation involved in ____(disease)___ is an in-frame (3 nucleotide) deletion leading to the deletion of a single phenylalanine.
Cystic fibrosis - deletion on the CFTR protein
In what pathway are misfolded proteins exported from the ER to the cytoplasm (via translocation machine) and targeted for degradation (via proteasome)?
Endoplasmic reticulum-associated degradation (ERAD) pathway
