Question

which of the following activity most likely lead to activation of protein kinase A

1. activation of p13 kinase and downstream Rac GTPase

2. cytosolic Catt change

3. activation of adenylyl cyclase by Gx subunit

4. activation of PLC by GBY subunits

the observation that G-actin subunits tend to be incorporated into F-actin at the barbed end and released from the pointed end is known as

1. treadmilling

2. dynamic instability

3. G-protein coupled incorporation

4. fluorescence recovery after photobleaching

Answer 1

Which of the following activity most likely lead to activation of protein kinase A

Correct option- 3. activation of adenylyl cyclase by Gx subunit

Justification- This is the correct option because activation of adenylyl cyclase by  GTP bound G-α subunit will result in increase level of cAMP which lead to activation of protein kinase A.

Reason for incorrect options-

1. activation of p13 kinase and downstream Rac GTPase

2. cytosolic Catt change

Option 1 and 2 are incorrect because these activity does not  lead to activation of protein kinase A

4.activation of PLC by GBY subunits

This is incorrect because activation of PLC leads to breakdown of phosphoinositol di-phosphate PIP2 into inositol triphosphate (IP3) and diacylglycerol (DAG) . It does not lead to activation of protein kinase A.

Question-the observation that G-actin subunits tend to be incorporated into F-actin at the barbed end and released from the pointed end is known as

Correct option-1. treadmilling

Justification- This is correct option because in  steady state, G-actin subunits tend to be incorporated into F-actin at the barbed end balanced by net loss of subunits at the pointed end and this process is called as  treadmilling.

Reason for incorrect option-

2. dynamic instability - This is incorrect because dynamic instability occurs when assembly and disassembly of actin occurs at one end only whereas in treadmilling assembly and disassembly of actin occurs at two different  end.

3. G-protein coupled incorporation

This is not correct option because this does not involve incorporation of F-actin at the barbed end and released from the pointed end.

4. fluorescence recovery after photobleaching

This is incorrect because fluorescence recovery after photobleaching refers to the study of movement of fluorescent labelled lipid or protein in cell.