Protein Modification

Question 1

N-Acetylation

Answer 1

from acetyl coA, in histones, relax association w DNA making available for transcription. Uses MAP to cut N off, NAT gives acetyl to lysine. MAP-NAT

Question 2

Acylation

Answer 2

attachment of FA, in small g-proteins w palmitic acid or myristic acid affects attachment to subcellular membrane

Question 3

ADP Ribosylation

Answer 3

Bacterial toxins (cholera, diphtheria, salmonella) ADP ribosylate target proteins such as G proteins

Question 4

Carboxylation

Answer 4

Attachment of carboxyl (COOH), Vit K dependent clotting factors are activated via carboxylation

Question 5

Disulfide bonds

Answer 5

Ox of sulfhydryl (SH) to disulfide (S-S) for stabilization of protein structure

Question 6

Glycation and glycosylation

Answer 6

Non enzymatic attachment of glucose, such as high levels of glycosylated by glycosyltransferases hemoglobin in poorly treated diabetics, glycosylation of bilirubin to make more water soluble for elimination. or glycosylation of erythrocyte membrane defines blood type.
Happens in ER and Golgi. Needs UDP sugar

Question 7

GPI (glycosylphosphatidylinositol)

Answer 7

GPI-linked proteins are attached to plasma membrane outer surface

Question 8

Hydroxylation

Answer 8

Vit C dependent hydroxylation of proline and lysine are essential for stable collagen

Question 9

Methylation

Answer 9

Methylation of histones tightens w DNA more, inhibiting DNA transcription

Question 10

Phosphorylation

Answer 10

By kinase or phosphatase is used to activate or inhibit function, often in cell signaling cascade

Question 11

Lipidation (Prenylation)

Answer 11

Lipidation of protein anchors them to inner plasma membrane

Question 12

Sulfation

Answer 12

attachment of sulfate group on fibrinogen (protein involved in coagulation) and gastrin (gastric acid secretion)

Question 13

Ubiquitination

Answer 13

Adding ubiquiting tags a protein for degradation by protease

Question 14

Hydrophilic PTMs

Answer 14

Hydroxylation, Phosphorylation, Glycosylation

Question 15

Hydrophobic PTMs

Answer 15

Methylation and Lipidation

Question 16

S- adenosyl methionine (SAM)

Answer 16

transfers methyl group (ex. DNA methylation for availability of transcription)

Question 17

Myristoylation

Answer 17

irreversible mod of glycine, for cell localization

Question 18

Palmitoylation

Answer 18

reversible mod of cysteine for subcell trafficking

Question 19

Proteolysis

Answer 19

Insulin activated by cutting off portion of protein that covers active site

Question 20

2 Types of glycosylation

Answer 20

O-linked- adds sugar to Serine or Threonine (O group)

N-linked- adds to N of Asparagine

Question 21

List of GAGs

Answer 21

Chondroitin, Keratan, Heparin, Dermatan, Hyaluronate

Question 22

Heparin

Answer 22

used as anticoagulant, binds to antithrombin which inhibits procoagulant proteases