Please answer the following. 1. Which elements would likely be found in a protei
ID: 268752 • Letter: P
Question
Please answer the following.
1. Which elements would likely be found in a protein functioning in signaling through a receptor tyrosine kinase? A. a covalent lipid-link to the membrane B. a B-barrel motif C. a calcium-binding domairn D. an SH2 domain E. a transmembrane domain 2. What is the connection between signaling through the following: adhesion receptors, voltage-gated ion channels, receptor tyrosine kinases, and microdomains (Le., rafts)? A. All are based on a conformational change in membrane proteins B. All of them are highly exergonic events C. All of them require increased concentrations of a second messenger. D. All of them are stimulated through phosphorylation. E. All of them begin with a ligand specifically binding a receptor 3. How does PLC activate PKC? A. It increases cAMP levels. B. It converts phosphatidylcholine to phosphatidic acid, which activates PKC. C. It converts phosphatidylcholine to DAG and phosphocholine to activate PKC. D. It converts phosphatidylinositol-4,5-bisphosphate to DAG and IP3 to activate PKC. E. GEF converts GDP-bound form to GTP bound form of PKC 4. Which enzyme involved in glycogenesis and glycogenolysis is allosterically regulated? A. GSK3 B. glycogen phosphorylase C. glycogen synthase D. PP1 E. All of the answers are correct.Explanation / Answer
1. D. Receptor Tyrosine kinase functions in trasmembrane signalling. This transmembane signaling relies highly on interactions that are mediated by SH2 protein domain.
3. D. Activation of PKC by VGEF is due to PLC activation products, DA and IP3. These can directly or indirectly activate PKC by Calcium mobilization.
4. B. Even C is correct in this case. Glycogen phosphorylase is widely studied for allosteric effects and is governed by AMP as allosteric effector. Infact glycogen phosphorylase is regulated allosterically as well as by phosphorylation.
While very less is known about this enzyme, it is true that the rraction is regulated greatly by allosteric effectors like glucose-6-phosphate. This enzyme may also regulated by phosphorylation.
2. A. In all cases, a conformational change in the protein occurs (including neuron and synapse change, in case of adhesion receptor, but they have no secondary messenger). Phosphorylation does not happen in all kinds of reaction. It is integral to teactions where secondsry messengers like cAMP or DAG etc are required.