Module 1 Part 2: Post-translational modification proteins

Question 1

Acetylation post-translational modification
example

Answer 1

Amine group of many amino acids
lysine residue R group
ex. histone modification to make DNA available for transcription

Question 2

Acylation post-translational modification
Example

Answer 2

Amine group on Glycine
R group on Cys, Serine/Threonine, Lys
Ex. acylation of G proteins affects membrane association

Question 3

ADP ribosylation post-trans mod
Ex.

Answer 3

Attachment of ADP ribose donated by NAD+
Occurs on: Cys R group, Aspartate/Glutamate and Arginine
Ex. Bacterial toxins affect signaling via ADP ribosylation

Question 4

Carboxylation post-trans mod
Example

Answer 4

Glutamate R group
Ex. Activation of vitamin K dependent clotting factors

Question 4

Disulfide bonds post trans mod
Example

Answer 4

Cysteine R groups (SH)
Ex. protein structure stabilization

Question 5

Glycation and glycosylation
Example

Answer 5

Glycation of Lys R group
Ser/Thr O-glycosylation R group
Asn/Gln N-glycosylation R group

Ex. Glycation is a symptom of diabetes
Ex. Glycosylation is how blood type is tagged

Question 5

GPI post-trans mod what is it?

Answer 5

Glycolipid attachment on outer surface of plasma membrane

Question 6

Hydroxylation post-trans mod
Example

Answer 6

Addition of OH
Ex. Structural stability of collagen depends on vitamin C-dependent hydroxylation of Pro/Lys
Pro/Lys R groups

Question 7

Methylation post-trans mod
Example

Answer 7

Addition of CH3
Arg, Lys, His, Asp, Glu, Cys R groups
Ex. Methylation of histones inhibits transcription

Question 8

Phosphorylation post-trans mod
Example

Answer 8

Ser, Thr, Tyr R groups
Ex. Activation/inhibition of proteins

HMGR is inactivated via phosphorylation by AMPK when [AMP] high, glucagon or sterols are high

HMGR is activated by HMGR phosphatase when insulin is high

Question 9

Prenylation post-trans mod
Example

Answer 9

Cys R group
Ex. Anchors proteins to inner leaflet of membrane

Question 10

Sulfation post trans mod
Example

Answer 10

Tyr R group
Sulfation of fibrinogen protein and gastrin hormone

Question 11

Ubiquitination post trans mod
Example

Answer 11

Lys R group
tags protein for degradation by proteasome

Question 12

Non standard AA examples

Answer 12

homocysteine, taurine, L-DOPA, hydroxyproline

Question 13

Why are proteins not stored?

Answer 13

it would cause uncontrolled metabolic activity