Serine in an amino acid chain, before and after<unk> . In chemistry,<unk>  of a molecule is the attachment of a phosphoryl group. This process and its inverse, dephosphorylation, are critical for many cellular processes in biology. Protein<unk>  is especially important for their function; for example, this modification activates (or deactivates) almost half of the enzymes present in Saccharomyces cerevisiae, thereby regulating their function. Many proteins (between 1/3 to 2/3 of the proteome in eukaryotes) are phosphorylated temporarily, as are many sugars, lipids, and other biologically-relevant molecules.
Phosphorylation
Hydrolysis
Redox
Demethylation
Hydroxylation
Acetylation
Excretion
Reuptake