Beyond the Ribosome

Question 1

Phosphates added to what amino acids drive the assembly of a protein into larger complexes?

Answer 1

Serine, Threonine and Tyrosine

Question 2

What happens if a methyl is added to lysine?

Answer 2

It creates distinct regions in chromatin through forming either mono-, di- or trimeythl lysine in histones

Question 3

What happens if acetyl is added to lysine?

Answer 3

It activates genes in chromatin by modifying histones

Question 4

What happens if a palmityl group is added on to cystenine?

Answer 4

It drives protein association with membranes

Question 5

What happens is N-acetylglucosamine is added to Serine or Threonine?

Answer 5

It controls enzyme activity and gene expression in glucose homeostasis

Question 6

What happens if ubiquitin is added to Lysine?

Answer 6

Regulates the transport of membrane proteins in vesicles

Question 7

Most signal sequences can form ….. helices?

Fill in the blank

Answer 7

Amphiapathic

Question 8

90% of proteins in the mitochondria are encoded by what?

Answer 8

Nuclear DNA

Question 9

What is chymotrypsin P175438?

Answer 9

It is a secreted zymogen (enzyme precursor).

Question 10

What does chymotrypsin P175438 do?

Answer 10

It contains an 18 residue signal peptide that targets it to the ER, which is then transported to the cell surface in the vesicles

Question 11

What is a transmembrane helix?

Answer 11

A protein with at least one transmembrane helical domain

Question 12

Are transmembrane helices hydrophobic or hydrophillic?

Answer 12

Hydrophobic

Question 13

What is the glycoslyation?

Answer 13

The addition of sugars to the side chains of certain amino acids

Question 14

What is N-linked glycosylation?

Answer 14

It is linkaged between Asparagine-any amino acid-Serine/Threonine

Question 15

What is O-linked glycosylation?

Answer 15

It is linkage between N-Acetylgalactosamine and Serine/Threonine

Question 16

What is N-linked glycosylation important for?

Answer 16

Protein folding; protein targeting

Question 17

Where does N-linked glycosylation occur?

Answer 17

Occurs initially in the ER and is refined in the golgi

Question 18

What is O-linked glycosylation important for?

Answer 18

It is complementary to protein phosphorylation for signalling

Question 19

Where does O-linked glycosylation occur?

Answer 19

Occurs in the cytosol

Question 20

What hydroxyl residues is phosphorylation most common on?

Answer 20

S, T and Y (to a much lesser extent on amino acids R, K, H)

Question 21

What is CDK2?

Answer 21

It is a kinase involved in signalling the cell cycle and it acts with its co-factor cyclin A

Question 22

Explain ubiquintation

Answer 22

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.

Question 23

What recognises specific patterns of polyubiquitinylation?

Answer 23

Proteasome (typically K48)

Question 24

K63 linked poly-ubiquintinylated proteins tend to be preferred for what?

Answer 24

Endosomal degradation

Question 25

What is P00740 Factor IX and what does it do?

Answer 25

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