Protein Kinase A Lab Report

The Protein Kinase A catalyzed phosphorylation that activate the phosphodiesterase, which is cleave the cAMP. In order to make the cAMP signal leading fast turnoff, the cAMP will stimulate degrade by its own. The part of a certain 5-amino acid sequence, which is hydroxyl group of serine and threonine. The Protein Kinase A transfer the Pi from ATP to that hydroxyl group. A complex of 2 regulatory subunits (R) and 2 catalytic subunits (C) are the resting state of Protein Kinase A existing. A pseudosubstrate sequence contains in each regulatory subunit (R) of Protein Kinase A that similar to the substrate domain of a target protein for Protein Kinase A, but alanine replacing for the threonine or serine. The pseudosubstrate domain of the regulatory subunit, can be phosphorylated if there are lacks a hydroxyl. The phosphorylated will binds to the active site of the catalytic subunit by blocking that one activity. A conformational change causes the regulatory subunits to relief the catalytic subunits once each regulatory subunit binds 2 cAMP. Then, the catalytic ( C) will catalyze phosphorylation of threonine or serine remains on target proteins. The activity of catalytic subunits ( C) can modulate by Protein Kinase Inhibitors.

The common sites for phosphorylation like protein of amino acid threonine and serine. Many enzymes that involved in intracellular signaling pathways are control by these phosphorylation reactions. The enzyme activity can be activate or inhibit depends on the addition of phosphate groups that cause the conformational change in enzymes. At certain time, the phosphate groups will eliminate from the enzymes by protein phosphatases in that way reversing the effect on enzymatic