Translation Flashcards
Start codon
AUG
Stop codons
UAA, UGA, UAG
Steps of tRNA “charging”
Forms aminoacyl-AMP via hydrolysis
tRNA synthetases must only join each amino acid to the tRNA that has the anticodon needed for that amino acid
Requires ATP Hydrolysis
Inosine can base pair with
U,C,A
Wobble position
Third position (on 5’ end)
What does wobble position allow
Same amino acid can come from different codons
Ribosomes are
Large ribonucleoprotein complexes conatining several rRNAs and many proteins
Initation of translation
1) CBP (cap-binding protein) binds to 5’ Cap of mRNA
2) Small ribosomal unit interacts with CBP complexed with 5’ Cap
3) Small subunit scans until it finds AUG (Kozak sequence)
Important initiation factor for initiation of translation
eIF-2
4 antibiotics that target translation
Chloramphenicol
Erythromycin
Tetracyclines
Streptomycin
IRE
Iron responsive elements found on mRNA
IRE-binding protein
Binds to IRE
IRE-binding protein binding pattern
Iron-bound IRE-BP cannot bind to IRE
Ferritin function
Iron storage protein
Transferrin receptor
Cell membrane protein that brings Fe into the cell
Low/high iron ferritin
Low - IRE-binding protein binds to IRE so translation inhibited
High - IRE-binding protein cannot bind so translation proceeds
Low/high iron transferrin
Low - IRE-binding protein binds to IRE to prevent degradation
High - IRE-BP cannot bind so degradation of mRNA occurs
HCI
Kinase inhibited by heme
Phosphorylates and inactivates eIF2, which decreases translation of mRNAs (including globin mRNAs)
eIF2
When not phosphorylated, increases translation of globin proteins
What rxn occurs to make disulfide bonds
Oxidation
O2—–H2O2
Insulin generated form -_____ and example of _____
Proteolysis of proteins
Proinsulin (also produces C peptide)
Digestive enzyme activation
Trypsinogen cleaved by enteropeptidase and trypsin into trypsin
Trypsin cleaves proelastase into elastase
Trypsin cleaves chymotrypsinogen into chymotrypsin
2 paths to apoptosis and where they converge
Fas and mitochondrion
Both cleave procaspase 3
Fas path to apoptosis
Fas receptor cleaves procaspase-8 into caspase 8…caspase 8 cleaves procaspase 3 into caspase 3…caspase 3 causes apoptosis
Mitochondrial path to apoptosis
Mitochondrion forms apoptosome…procaspase 9 cleaved to caspase 9…cleaves procaspase 3 into caspase 3
Clotting pathways converge ofn
Prothrombin
Hemophilia A
Low factor 8
Hemophilia B
Low factor 9
Hemophilia symtoms
Prolonged bleeding and bruising easily
Normal/alzheimer pathway of Abeta
alpha secretase
beta secretase
Protein phosphorylation occurs of
Serine, threonine, and tyrosine side chains
Phosphorylation regulates_______
The activities of proteins
Histone acetylation occurs on
Specific lysine residues (histones)
HAT/HDAC
HAT - Histone acetylation - opens the chromatin
HDAC - Histone deacetylation - silencing
Cancer cells and HDAC
Cancer cells use HDAC to turn off tumor suppressor genes by causing HDAC to be recruited to promoter
HDAC inhibitors used in
Cancers that suppress tumor suppressor genes
2 HDAC inhibitors
Trichostatin A
Trapoxin
Just eliminate enough HDAC to allow cells to die when treated with other therapies
p53 modification
Acetylated
Valproic acid
HDAC1 inhibitor that works on p53
Ubiquitination and when it happens
Targets proteins for degradation by protesosome
Damaged or regulated to degradation
Ras associates with membranes by
Side chain of a cysteine near C-terminus is liken to farnesyl (lipid group) by farnesyl transferase
FTI
Farnesyl transferase inhibitor - doesn’t allow attachment of farnesyl to Ras so therefore Ras cannot be incorporated into the membrane and cannot become active
