fosfoprotein

Fosfoprotein is a protein that carries covalently attached phosphate groups, usually added to serine, threonine, or tyrosine residues by kinases. Phosphorylation is a reversible post-translational modification driven by enzymes called protein kinases, which transfer a phosphate from ATP to target amino acids, and by protein phosphatases that remove these groups. Phosphorylation alters the chemical properties of the modified residue, often changing the protein’s activity, conformation, interactions with other molecules, stability, or subcellular localization. It is a central mechanism in cell signaling, metabolism, and cell cycle control, allowing rapid and regulated responses to extracellular cues.

In cells, proteins can become phosphorylated in response to signals such as growth factors, hormones, and stress. The phosphoproteome, the subset of the proteome that is phosphorylated, is dynamic and context dependent. Studying phosphoproteins commonly involves mass spectrometry-based phosphoproteomics and the use of phospho-specific antibodies.

Examples of phosphoproteins include milk casein, histone proteins that regulate chromatin structure, and numerous signaling proteins such as kinases, phosphatases, receptors, and transcription factors. Abnormal phosphorylation patterns are linked to diseases, including cancer, diabetes, and neurodegenerative disorders, and kinase inhibitors are widely used as targeted therapies.

See also: phosphorylation, protein kinase, protein phosphatase, phosphoproteomics.