Exam 3 - Protein Folding Flashcards
What are post-translational modifications?
Changes that happen after translation, to dictate shape and location.
How do proteins achieve their final conformation?
Linear sequence of amino acid dictates its final shape, happens through the help of chaperones and chaperonins.
Why is conformation important for proteins?
the two most important determinants/regulators of protein function are shape (conformation) and cellular localization. The protein must have the right shape and be localized in the right cellular location to be able to perform its job.
What’s the role of chaperons?
Prevent the formation of aggregates; keep proteins unfolded and allow proteins to fold at the right time. Also known as heat shock proteins. DON’T tell proteins how to fold.
What do Chaperonins do? How is that different from what chaperons do?
Chaperons help maintain the protein in an open conformation, therefore preventing aggregation and misfolding.
Chaperonins provide an “isolated” environment for proteins to fold in the absence of other interfering factors. “Fitting rooms”
What kind of physiological conditions trigger an upregulation in the synthesis of chaperons?
Heat shock and other stress conditions.
What’s the role of PDI (Protein Disulfide Isomerase)?
How does it contribute to protein folding? Does it play a role in the folding of cytosolic proteins?
Where is PDI located, i.e. in which cellular organelle?
Acts as a chaperone that increases the formation of disulfide bonds, which lead to the proteins’ proper form. In order for disulfide bonds to be stable, need to be in an oxidizing environment which is in the lumen of the ER, or extracellular matrix. Located in the ER.
Nucleus is reducing while the extraceullar environment, ER, golgi, vesicles and nuclear envelope are oxidizing to favor S-S
