L8: Regulation of Metabolic Pathways Flashcards
why is regulation needed
to maintain enery & cell/organism homeostasis
what is defective regulation linked to causing
diabetes, cancer, neurodegeneration
4 ways enzyme catalysed metabolic reactions are regulated
- Association with regulatory protein
- Sequestration (compartmentation)
- Allosteric regulation
- Covalent modification
what do allosteric modulators do to the enzymes
- change enzyme conformation & turn enzyme activity on/off
- enzyme can become more active
what major energy indicators in cells are often allosteric modulators of metabolic enzymes
ATP & AMP
NAD & NADH
what does covalent modification of an enzyme do
phosphorylation/dephosphorylation of an enzyme acts as a molecular switch & turns enzyme activity on/off
what does phosphorylation of an enzyme only occur on
Serine
Tyrosine
Histidine
Threonine amino acid residues
what is metabolic enzyme catalytic activity regulated by
- Amount of enzyme
- Association of enzyme w regulatory proteins
- Sequestration of enzyme
what are the 3 major hormones controlling enzymes in metabolism
insulin
glucagon
adrenaline
insulin mode of action
released from pancreas in response to increased blood [glucose]
glucagon mode of action
released from pancreas in response to decreased blood [glucose]
adrenaline mode of action
released from adrenal medulla in response to: decreased blood glucose conc., stress and anticipation of activity
how do hormones regulate metabolic enzyme activity
receptors respond to hormones and regulate the molecular enzyme catalysed. this signals cascades in the cell which in turn covalently modulates metabolic enzymes - e.g: by phosphorylation which turns enzyme activity on/off
what cell types do insulin & glucagon act on
insulin and glucagon act on specific receptors on many cell types - mainly liver & fat cells
what cell type does adrenaline act on
mainly skeletal muscle & fat cells
