Posttransational Protein Modification

Question 1

Acetylation

Answer 1

Attachment of acetyl group (COCHs); Ex. Histone relaxes making available for transcription

Question 2

Acylation

Answer 2

Attachment of acyl group (Fatty acid); Ex. Small G proteins (palmitic/myristic acid) affects attachment to subcellular membrane

Question 3

ADP ribosylation

Answer 3

Attachment of ADP ribose donated by NAD+; Ex. Bacterial toxins exert effect to target proteins

Question 4

Carboxylation

Answer 4

Attachment of carboxyl group (COOH); Ex. Vit. K dependent clotting factors are activated

Question 5

Disulfide bonds

Answer 5

Attachment of 2 cysteine residues to each other via oxidation of sulfhydryl (SH) bonds into disulfide bonds (S-S); Ex. stabilize protein

Question 6

Glycation/Glycosylation

Answer 6

Nonenzymatic attachment of glucose or enzymatic attachment of # and variety of sugars Ex. Increased glycated Hem. seen in Pt’s w/ uncontrolled DM; Glycosylation erythrocyte membrane define blood type

Question 7

GPI (glycosylphosphatidylinositol)

Answer 7

GPI linked proteins attached to plasma membrane outer surface; Ex. attached to protein outer membrane

Question 8

Hydroxylation

Answer 8

Attachment of OH group; Ex. Vit. C dependent form hydroxyproline/lysine to stabilize collagen

Question 9

Methylation

Answer 9

Attachment of CH3 donated by SAM (S adenosylmethionin); Ex. Tighten DNA; Inhibit transcription

Question 10

Phosphorylation

Answer 10

Attachment of phosphate group (PO4) via ester bond; Activates or inhibits function

Question 11

Prenylation

Answer 11

Attachment isoprenoids (Ex. farnesyl, geranyl); Ex. Anchor to inner cellular membrane

Question 12

Sulfation

Answer 12

Attachment sulfate group (SO4) from PAPs (phosphoadenosine phosposulfate); Ex. Perfomrmed on fibrinogen & gastrin

Question 13

Ubiquination

Answer 13

Attachment of small protein called ubiquitin; Ex. Tags proteins for degradation by proteasome