posttranslacionals

Posttranslational modifications (PTMs) are chemical changes that proteins acquire after synthesis on ribosomes. They expand the functional repertoire of the proteome by altering activity, stability, localization, and interactions. PTMs can be reversible or irreversible and may occur during folding, trafficking, or in response to cellular signals.

Common PTMs include phosphorylation, glycosylation, ubiquitination, acetylation, methylation, lipidation, and proteolytic processing. Phosphorylation, done by kinases, regulates signaling; ubiquitination often tags proteins for degradation; glycosylation influences folding and surface expression; acetylation and methylation affect chromatin dynamics and enzyme function; lipidation anchors proteins to membranes. Proteolytic processing by proteases can activate proteins or generate mature forms.

PTMs are catalyzed by enzymes such as kinases, phosphatases, ubiquitin ligases and deubiquitinases, glycosyltransferases, and proteases. They are studied with mass spectrometry–based proteomics, PTM-specific antibodies, and enrichment methods, revealing dynamic changes across conditions. PTMs often exhibit crosstalk, creating distinct functional states from combinations of modifications.

Biologically, PTMs regulate nearly all cellular processes, including signaling, gene expression, metabolism, and trafficking. Dysregulation of PTMs is linked to diseases such as cancer, neurodegeneration, and metabolic disorders. Ongoing research in proteomics, structural biology, and systems biology aims to map PTMs comprehensively and understand how modification networks coordinate protein function.