Question

9. What happens when a trimeric G a. Ga separates from b. GB separates from the GaG protein is activated by the GpGy dimer dimer d. Ga, Gp, and Gy separate from each other e. The trimeric G protein localizes to the c. Gy separates from the GaGß dimer t nuceus se the folowing list to answer questions 10-13.Answers can be used more than once a. Endocytosis followed by degradation in lysosomes tqitination mediated by SOCS followed by degradation by proteasomes c. Acetylation by a HAT leading to Securin binding d. Dephosphorylation by SHP1 e. Phosphorylation by kinases such as BARK or Rhodopsin kinase leading to Arrestin binding 10. Which is used for short-term (reversible) down-regulation of GPCR signaling? 11. Which is used for short-term (reversible) down-regulation of Cytokine receptor signaling? 12. Which is used for long-term down-regulation of Cytokine receptor signaling? Which is used for long-term down-regulation of RTK signaling? 13. Which statement about RTKs and cytokine receptors is false? 14. a. Both RTKs and cytokine receptors are active as dimers b. Individual subunits of both RTKs and cytokine receptors have one transmembrane alpha c. RTKs bind small charged molecule ligands, and cytokine receptors bind peptide/protein ligands y bind two s of ligand; active bind one. e. RTKs are kinases, while cytokine receptors are not but are tightly associated with JAK kinases 15. The TGFB signal transduction pathway is often inactivated in cancer. Which statement about the TGFB pathway is true? a. This pathway promotes entry into the cell cycle by altering gene regulation via MAP-Kinase. b. This pathway promotes entry into the cell cycle by altering gene regulation via STATs This pathway promotes entry into the cell cycle by altering gene regulation via PKC c. This pathway promotes entry into the cell cycle by altering gene regulation via PKB. d. e. This pathway prevents entry into the cell cycle by altering gene regulation via SMADs. Choose from the following five options to answer questions 16-19. Answers can be used more than once. a. Wee1 b. Cdc25 c. CAK d. Cyclin D. e. Cyclin B 16. Kinase that inhibits MPF activity by placing an inhibitory phosphate on MPF 17. Kinase that activates MPF activity by placing an activating phosphate on MPF 18. Protein that is part of MPF an activating Bhonale MP 19. Phosphatase that activates MPF activity by removing an inhibitory phosphate on MPF. 20. In mammalian apoptosis, which protein promotes apoptosis by making channels in the outer mitochondrial membrane that allows cytochrome c to leak into the cytoplasm? a. Smac/DIABLO b. Apaf-1. e. Bcl-2. c. Bad d. Bax.

Answer 1

9)G _α subunit separated from G_βG _γ dimer

G proteins have large extracellular binding domain when a appropriate protein binds to this domain the receptor undergoes a conformation change that is transmitted to its cytosolic region which activate trimeric GTP binding protein composed of alpha, beta and gamma both alpha and gamma are covalently attached to lipid and alpha subunit has GDP bound to it when a signal received the GDP is converted to GTP and the alpha subunit gets separated form beta and gamma complex.

10) Phosphorylation of kinases such as BARK or rhodopsin kinase leading to arrestin binding.

For the switch off of GPCR it down regulation is important for the that one of the mechanism is that the kinases phosphorylate the membrane associated G proteins as the phosphate block the docking site at the G proteins by which the trimeric GPCR proteins cannot bind to the GPCR receptor site thus how it is down regulated.

11) Dephosphorylation of SHP1

    Cytokine receptor consist of tow chains each having extra cellular space for binding of cytokines, in the presence of cytokine the two chains attach by to its site able to phosphorylate the tails of cytokine receptors which will attract the signal transduction hence will get phosphorylate and enters the cells for transcription and if the cytokine receptor are dephosphorylated then it can be down regulated.

12) Endoctyosis followed by degradation by lysosomes

The cytokines receptors attracts the MHC complex which present the defected cells to t cells leading to endoctyosis and degradation by lysosomes

13) Endoctyosis followed by degradation by lysosomes

Tyrosine kinase receptor attracts the proteins which will cause the endoctyosis and degradation of cells