Question

Protein phosphatases catalyze removal of phosphate groups from proteins. How would the activity of a protein phosphatase affect a cell's response to growth factors?

		a) Decrease proliferation
		b) Decrease glucose production
		c) Increase proliferation
		d) Increase glucose production

Answer 1

In fat, liver, and muscle, insulin stimulates the dephosphorylation of a number of enzymes involved in glycogen and lipid metabolism via activation of protein phosphatases.
Protein phosphatase-1 (PP1) is the primary phosphatase involved in insulin action.

• This means that, protein phosphatase lead to increased insulin synthesis, so, decreased glucose production.

​​​​

Protein phosphatase on proliferation :

• Progressive changes in protein phosphorylation control the transitions between different phases of the cell division cycle.
• Transitions between different phases of the cell cycle are controlled by post-translational changes of proteins.
• Protein phosphorylation is the most important post-translational modification.
• All the steps from entry into, continuation through, and exit from mitosis are all regulated by the phosphorylation of cell cycle-specific proteins.
• From studies, we knew that, protein phosphatase, they  decrease cell proliferation, and prevent premature transition to next cell cycle.