Protein phosphorylation is a post-translational modification that plays a central role in regulating signal transduction, the process by which cells communicate and respond to external stimuli. It involves the addition of a phosphate group to specific amino acid residues, typically serine, threonine, or tyrosine, within the protein sequence. This modification is mediated by specific protein kinase enzymes, which catalyse the transfer of phosphate from ATP to the target protein. Protein phosphorylation frequently acts as a molecular switch, altering the conformation, activity, localization, or interaction partners of the phosphorylated protein. One of the key roles of protein phosphorylation in signal transduction is the activation or inactivation of proteins. Phosphorylation can induce a conformational change that often activates the protein and enables it to carry out its function. For example, in the mitogen-activated protein kinase (MAPK) pathway, phosphorylation of MAPKs by upstream kinases leads to their activation, triggering a cascade of further phosphorylation events that ultimately regulates gene expression and cell proliferation. Conversely, dephosphorylation of proteins by protein phosphatases can inactivate them, shutting down signalling pathways. Protein phosphorylation also plays important roles in regulating protein-protein interactions and thereby modulates the formation of signalling complexes. For example, phosphorylation can create new binding sites for specific protein binding domains, enabling the recruitment of downstream effectors or adaptor proteins. One example of this is the phosphorylation-dependent interaction between the Src homology 2 (SH2) domain and phosphotyrosine residues, mediating the recruitment of proteins such as Grb2, which link receptor tyrosine kinases to the Ras signalling pathway. Moreover, phosphorylation also serves as a mechanism for signal amplification and integration. Upon ligand binding to a receptor, phosphorylation events can occur at multiple amino acid residues, leading to the recruitment of multiple downstream effectors simultaneously. This enables the integration of different signals into a coordinated cellular response. By example, phosphorylation of the insulin receptor substrate (IRS) proteins upon insulin stimulation allows the activation of multiple signalling pathways, including the PI3K-Akt pathway and the Ras-MAPK pathway. This integration of signals provides nuanced regulation of cellular processes such as metabolism, growth, and survival. Phosphorylation of proteins can also greatly affect protein stability, marking proteins for degradation or protecting them from proteolysis. The ubiquitin-proteasome system, responsible for targeted protein degradation, is often regulated by phosphorylation events. For example, phosphorylation of the tumour suppressor protein p53 can prevent its degradation, allowing it to accumulate and respond to DNA damage, thereby safeguarding genomic integrity. Finally, protein phosphorylation plays a critical role in cellular adaptation and response to environmental stimuli. In the context of stress response pathways, phosphorylation events can activate stress-activated protein kinases, such as c-Jun N-terminal kinases (JNKs) and p38 MAPKs. These kinases, upon phosphorylation, translocate to the nucleus and regulate the expression of genes involved in stress response, apoptosis, and inflammation. Thus, protein phosphorylation is a versatile and essential mechanism in signal transduction, controlling the activation and inactivation of proteins, regulating protein-protein interactions, and amplifying and integrating signals thereby playing a crucial role in coordinating complex signalling cascades within cells. We provide a wide product catalogue of research tools for investigating protein phosphorylation, including EGFR antibodies, CD45 antibodies, ErbB 2 antibodies, EGFR ELISA Kits, and ErbB 2 ELISA Kits. Explore our full protein phosphorylation product range below and discover more, for less. Alternatively, you can explore our Serine & Threonine Kinases, Tyrosine Kinases, and Tyrosine Phosphatases product ranges.