IBS I Exam II: Post Translational Modification

What protein is responsible for protein phosphorylation?

Protein Kinase

What protein reverses phosphorylation?

Protein Phosphatase

What is the target protein of histone acetylation

Histones

Histone Acetylation (HATs) impact on gene transcription

reduces the positive charge of the histone, weakening interaction with DNA, increasing transcription.

Histone deacetylation (HDACs) impact on gene transcription

Reverses acetylation, restoring positive charge on histones, increasing interaction with DNA, decreasing transcription.

What is the target functional group of o-linked glycosylation

Hydroxyl groups

What are the target residues of O-linked glycosylation

SYT

What is the target protein of N-linked glycosylation?

cell surface receptors

What are the target residues of N-linked glycosylation

Asparagine (N)

Target protein of protein hydroxylation

Collagen

What is the cofactor involved in protein hydroxylation

Vitamin C (Ascorbic acid)

What is the function of protein hydroxylation

Strengthens collagen triple helix structure

What is the mechanism of action of warfarin

Inhibits protein carboxylation, prevents blood clotting by preventing the reduction of oxidized vitamin K.

what is the cofactor of protein carboxylation?

Vitamin K

What is the biochemical impact and biological functions of fatty acylation?

Membrane targeting and protein-protein interactions

Chemical nature of ubiquitin

Small protein (76 amino acids) in all eukaryotic cells, contains N-terminal methionine, 7 lysine residues, and c-terminal glycine

Monoubiquitination

Ubiquitin forms isopeptide bond with epsilon amino group of lysine on target protein

What type of ubiquitination targets proteins for proteasome degradation, and what enzyme catalyzes the transfer of ubiquitin to the target protein?

Lysine (K) 48, E3 ubiquitin ligase