GENE 500 Lecture Notes - Lecture 3: Alternative Splicing, Protein Folding, IntronPremium
2 pages11 viewsFall 2018
Course CodeGENE 500
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Lecture 3 – Protein Evolution
Number of Proteins
Molecular chaperones, which bind to a short segment of a
protein substrate and stabilize unfolded or partly folded
proteins, thereby preventing these proteins from aggregating
and being degraded.
❑ Hsp70 and its homologs are the major chaperones in all
organisms that use an ATP-dependent cycle to fold their
Chaperonins, which form folding chambers into which all or part
of an unfolded protein can be sequestered, giving it time and an
appropriate environment to fold properly.
Proteins start to fold as soon as they come off the ribosome; but
it also as to avoid metastable states (that are too stable),
otherwise it will have a hard time coming out of it and continue
to fold until it reaches its native state of lowest energy
- Even though protein folding is thermodynamically stable,
kinetically, its not so good → hence, folding is assisted by
proteins to speed up the process
Why are there so few proteins even though there are so many combinations? It is because they
are very difficult to fold correctly
However, 100,000 proteins are still a lot of proteins, so why are there so many? This is due to
alternative splicing in eukaryotes (some introns are includes, some are removed, etc…)
→ Tissue Specific Adaptation: if you sequence a protein in tissue, it may have different
alternative splicing that if you sequenced it in another tissue
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