Serine is a non-essential amino acid involved in protein synthesis. It does not constitute an independent family but rather is a basic component of proteins. Present in all cells and tissues, serine participates in various biochemical reactions such as protein synthesis, phosphorylation reactions, one-carbon metabolism, and glutathione synthesis. The synthesis of serine is regulated by intracellular metabolic pathways, and changes in its levels can affect signaling pathways, such as phosphorylation events mediated by serine/threonine kinases. The specificity of gene expression and mutations are less directly associated with serine itself but rather affect enzymes and related proteins in its metabolic pathways.