Question

2. The cell line of S49 lymphomas is commonly used to study adenylate cyclase. There Are cells with mutations in some of the system components. The Wild variant of S49 expresses receptors for the hormone epinephrine. The following graph illustrates measurements made using membranes from a $49 mutant line. The data in the graph on the left represent wild cells incubated only with GTP (with) with the cholera toxin, GTP and NAD+ the beginning of the experiment. The Central graph is a repetition of the experiment using mutant cells. The graph at the end shows the link of epinephrine to the wild (square) and mutant (triangles) cells and GTP (EPI) or treated 1 hour earlier with time 0 in the graph, radioactive ATP was added at Wild Type Variant Binding 1000 1000 75아 50아 200 so epi con ep 0510 15 20 Minuteś 5 10 15 20 100 200 300 Minutes Epinephrine] (nM) A. How do you explain that low levels of cAMP can be measured in both cells in the absence of

Answer 1

Low levels of cAMP can be measured in both cells in absence of stimulation because the radioactive ATP was added when the experiment has not started. cAMP is basically a secondary messenger which helps in facilitating intracellular signal induction and produced from the ATP. Since during time = 0, ATP was present, it led to low level of production of cAMP and hence it can be determined that even without stimulation, the cAMP is present.