AP BIOLOGY

Detailed explanation-1: -Protein phosphorylation is one of the most common and important post-translational modifications (PTMs) (1, 2). This reversible mechanism occurs through protein kinases and consists of the addition of a phosphate group (PO4) to the polar group R of various amino acids.

Detailed explanation-2: -Phosphorylation introduces a charged and hydrophilic group in the side chain of amino acids, possibly changing a protein’s structure by altering interactions with nearby amino acids. Some proteins such as p53 contain multiple phosphorylation sites, facilitating complex, multi-level regulation.

Detailed explanation-3: -Protein phosphorylation is a posttranslational modification (PTM) consisting of the addition of phosphate groups to specific amino acid residues on proteins. This PTM has the potential to alter the stability, subcellular location, and enzymatic activity of proteins with diverse roles in cells.

Detailed explanation-4: -Phosphorylation is the addition of a phosphate (PO4) group to a protein molecule or a small molecule. It can also be thought of as the introduction of a phosphate group into an organic molecule.

Detailed explanation-5: -Protein phosphorylation is a cyclic process of opposing reactions. A kinase transfers the -phosphoryl group of ATP onto protein side chains and a phosphatase removes the phosphate by hydrolysis (Fig. 3). Each turn of the cycle results in net hydrolysis of a molecule of ATP (ATP + H2O = ADP + Pi).