Phosphorylation is a fundamental post-translational modification that plays a crucial role in regulating protein function and cellular signalling. Phosphorylation involves the addition of a phosphate group to specific amino acid residues within proteins, such as serine, threonine, and tyrosine. Phosphoserine and phosphothreonine are phosphorylated forms of the amino acids serine and threonine, respectively. These phosphorylated residues are commonly found in signalling proteins and frequently act as molecular switches in various cellular processes. They are primarily involved in mediating protein-protein interactions, modulating enzymatic activity, and regulating signal transduction pathways. One of the key features of phosphoserine and phosphothreonine is their negative charge. The addition of a phosphate group imparts a negative charge to these amino acids, altering their physicochemical properties and creating new interaction interfaces. This charge alteration allows phosphoserine and phosphothreonine residues to engage in electrostatic interactions with positively charged residues on specific protein domains, thereby facilitating protein-protein interactions critical for signalling events. Phosphoserine and phosphothreonine play multifaceted roles in cell signalling. They are involved in numerous signal transduction pathways, including those activated by growth factors, hormones, and stress signals. These phosphorylation events frequently serve as key regulatory steps, influencing the activation or inhibition of downstream signalling cascades. For example, phosphorylation of serine and threonine residues within the activation loop of protein kinases such as S6K and Akt can regulate their catalytic activity. Activation loop phosphorylation often triggers conformational changes, allowing the kinase to adopt an active state and initiate phosphorylation of downstream targets. Conversely, dephosphorylation of these residues can lead to kinase inactivation, terminating the signalling cascade. Phosphoserine and phosphothreonine residues also serve as recognition motifs for specific protein domains that facilitate protein-protein interactions necessary for signal transduction. These interactions can be crucial either for the assembly of signalling complexes, or for the recruitment of downstream effectors. For example, the phosphoserine or phosphothreonine motifs present in the 14-3-3 protein-binding domain allow the 14-3-3 proteins to interact with a wide range of phosphorylated targets, influencing their localization, stability, and activity. Finally, in addition to their direct effects on protein function, phosphoserine and phosphothreonine modifications can also regulate protein stability and degradation. Phosphorylation of specific serine or threonine residues for example can create recognition sites for E3 ubiquitin ligases, leading to protein ubiquitination and subsequent proteasomal degradation. We provide a comprehensive product catalogue of research tools for investigating phospho Ser and phospho Thr, including ICAM3 antibodies, RICTOR antibodies, and MEK5 antibodies. Explore our full phospho Ser and phospho Thr product range below and discover more, for less.