Regulation of Enzymatic Activity. Lesson 4

Regulation of Enzymatic Activity Lesson 4

Regulation of Enzymatic Activity no real regulation: - regulation of enzyme expression and turnover - control of enzyme trafficking - supply of cofactors real regulation of enzymatic activity: - activation/inhibition by small-molecule ligands - activation/inhibition by protein binding - activation/inhibition by regulatory domains - activation/inhibition by covalent modifications - activation by proteolytic cleavage - regulation by physical conditions

Regulation of enzyme expression and turnover and control of enzyme trafficking + RNA polymerase + transcription factors represors +/ steroid hormones DNA RNA protein RNases proteases

Activation/inhibition by small-molecule ligands regulation: activation/inhibition regulation: non-allosteric/allosteric inhibition: competitive, noncompetitive, acompetitive, covalent parameters: saturation constant, inhibition constant, IC50

Activation/inhibition by small-molecule ligands second messengers: camp, cgmp diacylglycerol IP 3 and other inositol phosphates Ca 2+, calmodulin prostaglandins NO, 2, CO ethylene, ppgpp, others

Activation/inhibition by small-molecule ligands feedback regulation of metabolic pathways: Pasteur effect: anaerobic glycolysis is faster than aerobic - phosphofructokinase is activated by ADP, AMP, fructose-2,5-bisphosphate, inhibited by ATP and citrate - pyruvate kinase is inhibited by ATP

Activation/inhibition by protein binding - activator/inhibitor proteins cyclin cyclin P CDK CDK CDK INK4 p27 cyclin

Activation/inhibition by regulatory domains regulatory (adaptor, interaction) domains 3 2 rc kinase PTPLC (phosphatase) 2 2 PLCγ1 P EF-hand P 2 3 2 P C2 (phospholipase) Ras activator (activates GTPase) 2 3 2 P Vav guanine nucleotide exchange protein 2 3 2 C-Crk 3 2 2 Crb2 2 3 2

Activation/inhibition by regulatory domains regulatory (adaptor, interaction) domains 2 domain (rc-homology type 2) protein kinases, protein phosphatases, phospholipases, regulatory proteins and others -py x x Φ-

Activation/inhibition by regulatory domains regulatory (adaptor, interaction) domains 3 domain (rc-homology type 3) protein kinases, protein phosphatases, phospholipases, regulatory proteins, myosin, spektrin and others -R/K x x P x x P- -x P x x P x R/K-

Activation/inhibition by regulatory domains regulatory (adaptor, interaction) domains P domain (Pleckstrin-homology) phospholipases, protein kinases and others inositole phosphates (PIP 2, PIP 3 ), free or in phospholipids

Activation/inhibition by regulatory domains regulatory (adaptor, interaction) domains E2 domain (Eps15-homology type 2) clathrin adapter proteins -/T N P F Φ-

Activation/inhibition by regulatory domains regulatory (adaptor, interaction) domains PDZ domain (abbreviation of a very long name) CFTR - Cystic fibrosis transmembrane conductance regulator C-terminal peptides

Activation/inhibition by covalent modification phosphorylation/dephosphorylation ATP protein kinase ADP Protein O- Protein O-PO 3 2 Pi protein phosphatase water

Activation/inhibition by covalent modification phosphorylation/dephosphorylation Enzyme Protein kinase A (PKA) Protein kinase B (PKB) Protein kinase C (PKC) CaM-PK AMPK MAPK Insulin receptor rc, Abl, Jak... Activator camp PtdInsP3 DAG Ca2+ - calmodulin AMP phosphorylation insulin phosphorylation and others

Activation/inhibition by covalent modification phosphorylation/dephosphorylation glucagon GPCR + adenylate cyclase camp PKA phosphorylase kinase inactive phosphorylase active phosphorylase protein phosphatase insulin

Activation/inhibition by covalent modification other modifications ADP-ribosylation on Arg adenylation on Tyr others

Activation by limited proteolysis trypsinogen trypsin

Activation by limited proteolysis apoptosis Apoptosome cyt. c FA receptor Caspase 9 Caspase 8 Oxidation stress, radiation etc. Caspase 3 Caspase 6 Caspase 7

Activation by limited proteolysis blood coagulation kallikrein XII XIIa XI XIa IX IXa X Xa II IIa (thrombin) fibrinogen fibrin polymer XIII XIIIa cross-linked polymer

Allosteric effect homo/heterotropic positive/negative

Allosteric effect ill's model = A κ A κ + K Aldair's model Monod-Wyman-Changeux model Koshland's model

Abelson protein kinase 3 P 2 3 kinase domains 2 kinase domains kinase domains P 3 2 kinase domains 2 3 3 2 kinase domains

Abelson protein kinase Chromosome 22 9 Philadelphia BCR 3 2 kinase domains BCR 3 P 2 kinase domains P