Beyond the Ribosome Flashcards
Phosphates added to what amino acids drive the assembly of a protein into larger complexes?
Serine, Threonine and Tyrosine
What happens if a methyl is added to lysine?
It creates distinct regions in chromatin through forming either mono-, di- or trimeythl lysine in histones
What happens if acetyl is added to lysine?
It activates genes in chromatin by modifying histones
What happens if a palmityl group is added on to cystenine?
It drives protein association with membranes
What happens is N-acetylglucosamine is added to Serine or Threonine?
It controls enzyme activity and gene expression in glucose homeostasis
What happens if ubiquitin is added to Lysine?
Regulates the transport of membrane proteins in vesicles
Most signal sequences can form ….. helices?
Fill in the blank
Amphiapathic
90% of proteins in the mitochondria are encoded by what?
Nuclear DNA
What is chymotrypsin P175438?
It is a secreted zymogen (enzyme precursor).
What does chymotrypsin P175438 do?
It contains an 18 residue signal peptide that targets it to the ER, which is then transported to the cell surface in the vesicles
What is a transmembrane helix?
A protein with at least one transmembrane helical domain
Are transmembrane helices hydrophobic or hydrophillic?
Hydrophobic
What is the glycoslyation?
The addition of sugars to the side chains of certain amino acids
What is N-linked glycosylation?
It is linkaged between Asparagine-any amino acid-Serine/Threonine
What is O-linked glycosylation?
It is linkage between N-Acetylgalactosamine and Serine/Threonine
What is N-linked glycosylation important for?
Protein folding; protein targeting
Where does N-linked glycosylation occur?
Occurs initially in the ER and is refined in the golgi
What is O-linked glycosylation important for?
It is complementary to protein phosphorylation for signalling
Where does O-linked glycosylation occur?
Occurs in the cytosol
What hydroxyl residues is phosphorylation most common on?
S, T and Y (to a much lesser extent on amino acids R, K, H)
What is CDK2?
It is a kinase involved in signalling the cell cycle and it acts with its co-factor cyclin A
Explain ubiquintation
The ubiquitin peptide is not synthesised by the cell in its final form but is part of either ribosomal proteins (the ubiquitin peptide is the n-terminal portion of the gene which gives a peptide which is cleaved to give ubiquitin and ribosomal protein) or a poly-ubiquitin protein.
C-terminus of ubiquitin forms a peptide bond with the lysine side chain.
What recognises specific patterns of polyubiquitinylation?
Proteasome (typically K48)
K63 linked poly-ubiquintinylated proteins tend to be preferred for what?
Endosomal degradation
What is P00740 Factor IX and what does it do?
Signal sequence which targets to ER; Recognition sequence which is cted on by gammacarboxylase in ER and is glycosylated for folding, and is excreted via exocytosis
