Allosterism, Enzyme Regulation
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- What does an allosteric inhibitor do? Give an example.
- An allosteric inhibitor decreases enzyme affinity for a substrate. An example is ATP.
- Which allosteric inhibitor is part of the TCA cycle in mitochoncria that prouduced ATP?
- citrate.
- For a cell to have a particular enzyme activity, what two things must a gene have?
- presence and expression.
- A cells activity depends on these four things
-
1. substrate specifity,
2. Km,
3. concentration of reactants,
4. allosterism (activating or inhibiting) - Name five enzyme regulating processes.
-
1. Post-translational modification,
2. Binding regulatory molecules,
3. Protein-Protein interactions
4. Targeted Degregation
5. Protein Phosphorylation - this mechanism for enzyme regulation turns enzymes on and off, an example is protein phosphorylation
- Post-translational modifications
- Binding of regulatory proteins may also do what to enzymes and other proteins?
- signal their molecules
- Enzymes in a complex with regulatory subunits that affect the activity of the enzyme is called what?
- Protein-Protein interactions
- The specific degregation of proteins is another way that cells can regulate enzymes expressed by cells is called what?
- Targete degregation.
- How many processes does Protein Phosphorylation involve?
- Two.
- What two distinct processes does protein phosphorylation involve?
-
1. Enzymes called kinases transfer phosphate from ATP to protein substrate,
2. Enzymes called phosphatases cleave phosphate from the protein to return the protein to original state and release inorganic phosphate. - Which steps have kinases and phosphatases in protein phosphorylation?
- Kinases are in the first step, phosphatases are in the second step.
- Phosphorylation provides a mechanism for what?
- reversible modification of proteins to regulate their functions.
- Does phosphoylation happen only in multicellular organisms?
- No, this protein mechanisms enzymes is found in bacteria and algae as well.
- What are the products of protein kinases?
- phospholated protein and ADP
- What are six examples of protein kinases given?
- PKA, PKC, CaM kinase, cdk, MLCK, src
- What are PKA, PKC, CaM kinase, cdk, MLCK, src protein kinases?
-
1.PKA: cyclic AMP-dependent protein kinase
2.PKC:Ca2+/phospholipid-dependent kinase
3.CaM kinase: calmodulin-dependent kinases
4.cdk: cyclin-dependent kinase
5.MLCK: myosin light chain kinase (role in contraction of smooth muscle cells)
6. src: transforming gene from avian sarcoma virus - How many kinases in the human Kinome?
- 500 kinases.
- How are protein phosphatases ordered?
- Type 1, 2A, 2B
- What are the two products of protein phosphophatases?
- dephosphorylated protein and Pi
- Okadeic acid (shellfish/red tide) and microcystins (produced by toxic blue/green algae)are newly discovered toxins and liver carcinogens are also what?
- Phosphatase inhibitors
- What has wider substrate specificity than protein kinases?
- Protein Phosphates.
- What has wider substrate specifity than protein kinases?
- Protein Phrosphatases.
- In specific sequences on the surface of protein hydroxyl-containing amino acids in specific sequences are what?
- Phosphorolation sites in proteins
- Kinases do what two things?
- utilize ATP by attaching it to a protein amino acid and recognizes substrates
- Kinases are made from what groups?
-
A) Ser/Thr
B) Tyr
C) Both Ser/Thr and Tyr - Ser/Thr kinases are what?
- Short akile groups only differing by the CH2 group
- Tyr kinases are what kind of group?
- Big Bulky groups.
- What does "dual specificity" in kinases mean?
- The kinases are both Ser/Thr and Tyr. (they are both short akile groups with differing CH2 groups and big bulky groups)
- What are the specificites of kinsases?
- Ser/Thr, Tyr or both
- Specificity is determined by what two things?
- the protein expresse in the cell and the local area of the cell
- What reflects the expressed protein?
- The cells phenotype
- What is often the same from cell to cell for a protein to be expressed?
- kinases
- What is the same for a protein to be expressed in a cell?
- second messangers/activators (cAMP, Ca^2+, DG ext.
- Cells use their priming to react to kinases as what happens?
- Phosphorolation of the cells.
- Substrate proteins that a cell expresses gives rise to what?
- the cell's specific response
- Many genes need to be turned on for critical steps in this complex mechanism, such as the critical central pathway, 4 kineases and the lots of genes involved
- Phosporylation cascades
- Phosphorylation cascades allows for what kind of network?
- hiarchal network
- glycogen->glucose->pyrate mechanism does what?
- In phosphorylation cascades it activates one an inactivates the other pathway back tracking like veins and arteries.
- What are two purposes of phosphorylation cascades?
-
1. initiation of cell growth
2. control of glucose metabolism - In phosphorylation cascades the breakdown of glycogen in the process of glycolysis forms what, to do what?
- ATP is formed in glycolysis to initate cell growth.
- the synthesis of glycogen is also called what?
- gluconeogenesis
- What is the difference between glycolysis and gluconeogenesis?
-
glycolysis is the breakdown of glycogen to form ATP,
gluconeogenesis is the synthesis of glycogen - turn on glycolysis and inhibit gluconeogenesis (or vice versa) so
- active and inactive enzymes swootch on and off during phosphorylation