With regard to the action of phospholipases C-B and C-y on phosphatidyl inositol, all of the following statements are true EXCEPT: The products of the reaction can stimulate Ca2+ release. The reaction products resulting from phospholipase C activity stimulate adenyl cyclase O Phospholipase C-Bß and C-y are activated by different receptor families which lie upstream of these lipases. The enzymes cut between the diacylglycerol (DAG) and inositol phosphate (IP3) moieties. Phospholipase C-B and C-y are both calcium dependent.

EGTA is a chelating agent that binds to Ca2+ with a high affinity and specificity. An experimenter may prevent increasing cytosolic Ca2+ from climbing over 10-7 M by microinjecting a cell with an adequate EGTA solution. What effect will EGTA microinjection have on the?-adrenergic and?-adenergic pathways in a cell?

After establishing the importance of cGMP in the signaling pathway of the photoreceptor cells, the researchers wish to identify the exact target of cGMP. The researchers suspect that cGMP binds to an ion channel, causing the observed change in the membrane potential between the dark and the light conditions but they are not sure which one. The researchers determine the movement of three different ions (sodium, chloride and potassium) as a function of their respective electrochemical gradient across the plasma membrane: ● Sodium tends to enter the cell Chloride tends to enter the cell Potassium tends to leave the cell The researchers therefore propose three simple hypotheses for the effect of cGMP on the membrane potential of the rod photoreceptor cell: ● Hypothesis A: CGMP binds to a sodium-channel, that opens and lets sodium ions diffuse inside the cell. Hypothesis B: cGMP binds to a chloride-channel, that opens and lets loride ions diffuse inside the cell. Hypothesis C: cGMP binds to…

The brain is fueled almost exclusively by glucose. Using this fact, would it be a good idea to express glucose-1-phosphatase in muscle? What type of phenotype would be exhibited by a mouse expressing glucose-1-phosphatase in muscle?