Which of the following statements best defines the term ‘spare receptors’? ‘Spare receptors’ refers to receptors that are broken down by cells because they are surplus to requirements. ‘Spare receptors’ occur when the KD for agonist binding to the receptor is smaller than the EC50 determined for a particular physiological response. ‘Spare receptors’ refers to the pool of intracellular receptors that are able to translocate to the plasma membrane. ‘Spare receptors’ can be defined as the number of receptors not occupied by agonist when a maximal response has been achieved, compared to the total number of receptors in the cell.

You are studying the role of CAMP in cell signaling. You hypothesize that 2 intracellular signaling proteins, named GO and TIGERS, interact with each other when cells are treated with an extracellular source of CAMP. The two proteins were tagged with CFP or YFP (CFP = cyan fluorescent protein; YFP = yellow fluorescent protein). CFP is excited by 435 nm light and emits lights at 480 nm. YFP is excited by 480 nm light and emits light at 535 nm. 400 500 Wavelength of Emitted Light 400 500 Wavelength of Emitted Light 600 600 Fluorescence 400 400 500 Wavelength of Emitted Light 600 500 Wavelength of Emitted Light 600 Fluorescence Intensity 400 500 Wavelength of Emitted Light 600 Figure Legend. A. Cells expressing GO-CFP irradiate with 435 nm light. B. Cells expressing TIGERS-YFP and irradiated with 435 nm light. C. Cells expressing TIGERS- YFP and irradiated with 480 nm light. D. Cells expressing GO-CFP and TIGERS-YFP and irradiated with 435 nm light. E. Cells expressing GO-CFP and…

You are studying a pathogenic bacterium which secretes a toxin that affects G protein receptor signaling. You perform a preliminary experiment in which you examine intracellular CAMP levels in untreated and toxin treated cells. The data is in the figure below. How does the toxin affect CAMP levels due to G protein receptor signaling? Select all that apply CAMP levels 250 200 150 100 50 0 no Toxin with Toxin The toxin stimulates GTP binding to the Gas subunit The toxin stimulates GTP binding to the Gai subunit The toxin inhibits GAP or GTPase activating proteins The toxin stimulates adenylyl cyclase activity

The dissociation equilibrium constant (Kd) is:_____ (select all that apply) Group of answer choices: Is a measure of ligand efficacy Typically equivalent to 1- Ka The concentration of ligand that gives maximal receptor occupancy The concentration of ligand that gives half-maximal receptor occupancy Measured in 1/M or M-1 Typically measured in mol/L or M A measure of the strength of a ligand - receptor binding reaction

Binding of talin induces a separation of α and β subunits and induces conformational changes that results in the Integrin to bind extracellular matrix ligands. This is an example of    Question options:   Fibronectin   Inside-out signaling   Outside-in signaling   All of the above

Which of the following is most likely an example of signaling through a transmembrane receptor? The influenza virus recognizes specific proteins on the surface of host cells, causing the entrance of genetic materials into the cytoplasm of the host cells.  Low-density lipoproteins (LDL) bind to receptor proteins found on the membrane of receiving cells, triggering its internalization into the receiving cells. The binding of interleukin-6 (IL-6) to the interleukin-6 receptor causes the activation of protein kinases in the cytoplasm, activating the transcription factor NF-κB. The binding of aldosterone to the aldosterone receptor activates its transcription activity, leading to the transcription of genes that promote the uptake of ions and water.

It is important for the cell to be able to terminate responses, and diminish responsiveness to prevent overstimulation.  Cells have different mechanisms for this. One such mechanism is receptor down regulation. a.) Down regulation describes a decrease in the availability of hormones or neurotransmitters that bind to receptors on the surface of target cells, making the cells less likely to be stimulated.   b.) Down regulation describes glycosylation of receptor proteins receptors on the surface of target cells in order to decrease the selectivity of ligand binding, making the cells less sensitive to a hormone or neurotransmitter.   c.) Down regulation describes a decrease in the number of receptors on the surface of target cells, making the cells less sensitive to a hormone or neurotransmitter.

3) The “Met" receptor is a membrane receptor protein responsible for initiating signal transduction pathways that cause cells to divide, among other things. After the Met receptor has been stimulated by its specific growth factor, another protein called c- Cbl will bind to the Met receptor. C-Cbl will then attach a chain of small proteins called ubiquitin to the Met receptor. These chains of ubiquitin help the cell recognize that the Met receptor should undergo receptor-mediated endocytosis, which eventually leads to the destruction of the Met receptor. Circle any answer or answers that include mutations that could cause the cell to potentially become a cancer cell. A) a mutation causing there to be too much ubiquitin protein produced. B) a mutation causing c-Cbl to be inactivated. C) a mutation causing ubiquitin to be inactivated. D) a mutation causing there to be too few Met receptors produced. E) a mutation causing the Met receptor to no longer be able to bind to its growth factor.…

Suppose that a G protein undergoes a mutation that allows the exchange of bound GTP for GDP to occur in the absence of G protein binding to a re- ceptor. How might this mutation affect signaling involving a GPCR? Which subunit of the G protein is most likely affected by the mutation?

GTP binding proteins are molecular switches. How do GTP binding proteins work? Provide two examples of GTP binding proteins that function in intracellular protein transport. Make a drawing that illustrates the function of each of these proteins in their respective roles. Predict the direct outcome of a mutation that: Inhibits GTPase activity Inhibits interaction with the GEF