Lecture 12 Flashcards
What is a proteosome’s function?
Degradation of misfiled day proteins that have been ubiquity a Ted (this means that it is misfolded)
What is the anticodon on tRNA?
the part that binds to the nucleotides codon of mRNA and therefore helps be sure the correct AA is added to the peptide chain
What is a ribozyme?
an RNA molecule that is capable of acting as an enzyme
ex. Ribosomes are ribozymes (2/3rds of ribosome components are RNA)
What are molecular chaperones? how are they triggered?
proteins that help refold misfolded proteins (uses ATP)
they recognized hydrophobic stretches of AA’s on the surface of a protein (this means it is misfolded because hydrophobic portions should be on the inside of the protein)
What is a proteasome? how is this related to protein folding?
a compartmentalized (cap and inner cylinder) protease with sequestered active sites that eliminates misfolded proteins prior to aggregation occurs
the “cap” binds to mislfolded proteins and unfolds them and the active sites degrade proteins so that their AA’s can be recycled
what are heat shock proteins?
a type of chaperone protein that consume ATP in order to refold heat-damaged proteins
GroES cap contains the protein while it is being refolded, and eventually releases it
What are some diseases of proteopathy caused by aggregations of misfolded proteins?
Alzheimer’s, Parkinson’s, and prion diseases
What are some diseases of proteopathy caused by aggregations of misfolded proteins?
Alzheimer’s, Parkinson’s, and prion diseases
what must happen prior to protease degradation of a misfolded protein?
specialized proteins (E3 ligases) must ID misfolded proteins by ubiquitinating them
mRNA the require the aid of selenocysteine require a ______ before tRNA-Sel will bind to the designated stop codon.
secondary structure (Translation factor with GTP)
What is nonsense mediated decay?
it is a quality control mechanism used to prevent the translation of damaged mRNA that occurs during the “handoff” at the nuclear pore”
a ribosome uses ATP to do a “test run” on the mRNA to look for EJC’s and to check that a stop codon was the last exon.
if the test goes poorly, Upf proteins trigger mRNA degradation
During the initiation of translation, the Poly A tail of the mRNA must be bound to what? why must this occur?
elF4G binding protein to ensure that both ends of the mRNA are intact prior to translation begins.
Does the elF4G protein binding (via poly A binding) to the poly A tail of mRNA require energy? if so, what kind how how much?
Yes ; 2 GTP
