There are several common steps at the beginning.
- The transmembrane receptor binds to the ligand in the extracellular medium
- The receptor changes its conformation, inside the cell this change allows the receptor to interact with a G protein, which is anchored to the cell membrane too
- This interaction makes the G protein to substitute its GDP for GTP
- The G protein separates its subunits (alpha, beta and gamma) into alpha and beta-gamma (alpha goes by itself)
- This subunits may go to continue different signaling cascades, until alpha hydrolyzes its GTP into GDP, then the subunits attach again into a complete G protein in the cell membrane
3. Describe general mechanism of G-protein-linked receptors activating G proteins to relay signal from extracellular space...
Q17: G protein coupled receptors have two cavities, one opened towards the extracellular space and one opened towards the cytosol. What binds to the cavity opened towards the cytosol?
Choose all of the following that are differences between kinase receptors and G- protein linked receptors. a) Kinase receptors span the membrane one time while G-protein linked receptors span the membrane many times b) Kinase receptors phosphorylate other proteins while G-protein linked receptors do not c) There are no differences between Kinase and G-protein linked receptors d) G-protein linked receptors bind to steroids while kinase receptors do not e) G-protein linked receptors are are attached to a G protein while...
-Trace the general mechanism by which a signal transduction pathway occurs (i.e. from signaling molecule to response) Describe the two ways in which signaling proteins act as molecular switches -Which amino acid residues do kinases typically add phosphate groups? Distinguish between the two types of G proteins -What proteins regulate GTP-binding protein (G proteins) in terms of activation and inactivation? - Distinguish between the three main classes of cell surface receptors. -Trace the general mechanism by which a signal transduction...
Describe the main mechanisms by which newly synthesized proteins are transported from the cytosol to mitochondria and outline the importance of signal sequences and protein processing in the localization of proteins within the different compartments of the mitochondrion.
5. Many proteins are glycosylated via 0- or N-linked sugars. Describe N-linked protein glycosylation and its processing. 3 marks
Question 6 You and your G-protein coupled receptors o You have encountered G-protein coupled receptors in Intro Bio I lecture (or soon will), and will encounter them briefly again in Intro Bio II. You will spend 2 or 3 lectures on them in Cell Bio. They are integral (transmembrane) proteins embedded in the plasma membrane of every eukaryotic cell in your body. We will treat them as being 50 Angstroms in diameter. Considering the plasma membrane scaled up to the...
10. Describe how different G protein-coupled receptors can give rise to the synthesis of different 2nd messengers. EXTRA 5 points: Name three such G protein-induced 2nd messengers and name their subsequent target. 10. Describe how different G protein-coupled receptors can give rise to the synthesis of different 2nd messengers. EXTRA 5 points: Name three such G protein-induced 2nd messengers and name their subsequent target.
Describe how the signal transduction pathway that involves G proteins is similar to the signal transduction pathway involving inositol triphosphate. In a second paragraph describe how these 2 signal transduction pathways differ from one another. In a third paragraph describe how these 2 pathways are turned off.
INFORMATION ABOUT IMAGE G FOR QUESTIONS 12-15: GABAB receptors (GABABRs) are G-protein-coupled receptors that can be found on both pre- and postsynaptic neurons. When they are activated by GABA, they can have a range of effects. For the synapse you are studying in the following questions, the effects of GABABRs are indicated in IMAGE G. You are doing a series of experiments in which you are recording from the pre- and postsynaptic cell at a synapse. The experiments described below...
Match the following: Integral (intrinsic) membrane proteins Transmembrane protein Porins C-- Lipid-linked proteins Peripheral (extrinsic) proteins 1. Channel-forming proteins found in the outer membranes of bacteria, with a beta-barrel motif. 2. Proteins that are associated with membranes, but can be dissociated by relatively mild procedures. 3. Proteins that completely span the membrane. 4. A general class of proteins that are tightly bound to membranes by hydrophobic interactions. 5. Membrane-associated proteins that have covalently-bonded lipids.