11. Translation Flashcards
What are the key components for translation?
mRNA tRNA rRNA Ribosomal proteins Release/termination factors
What binds to the acceptor arm of tRNA?
Amino acids
What couples amino acids to the correct tRNA?
Aminoacyl-tRNA-synthetases
What is the A site on the ribosome?
Aminoacyl site
Acceptor site for next tRNA
What is the P site on the ribosome?
Peptidyl site
Contains amino acid chain
What is the E site on the ribosome?
Exit site
Harbours deacylated tRNA on its way out of the ribosome
What happens during initiation?
Assembly of: ribosomal subunits, mRNA, tRNA, GTP, initiation factors
Recognition of the start codon bu a tRNAmet molecule (enters P position)
What happens during elongation?
Next tRNA delivered to A site
Peptide bonds formed between the amino acids with the enzyme peptidyltransferase
Ribosome moves onto next codon
What happens during termination?
Termination codon arrives at A site
Stop codon is recognised by a release factor
RF binds to A site which causes protein to be released and disassembly of tRNA-ribosome-mRNA complex
How can protein activity be regulated?
Protein levels Protein location and conc Ligand binding Cofactor requirements Post-translational modifications
How is lysosomal degradation carried out?
Lysosomes have degradative enzymes that are only active at low pH
Degrades any protein that is released into lysosome
How is proteasomal degradation carried out?
Proteins can be labelled for degradation: polyubiquitination
Then can be recognised by proteasome and degraded
What are some common post-translational modifications?
Ligand binding Phosphorylation Cleavage to produce active protein/enzyme Ubiquitination Fatty acid modification Glycosylation
What amino acids can be phosphorylated?
Serine
Threonine
Tyrosine
What is the function of phosphorylation?
Alters protein function
Marks for degradation
Alters localisation
Promotes interactions
