Docking proteins are substrates of tyrosine kinases and function in the recruitment and assembly of specific signal transduction molecules. There are five members in p62dok family including p62Dok (Dok-1), p56Dok-2 (Dok-2, or DoK-R), Dok-3, Dok-4 and Dok-5 (1–3), which are characterized by the presence of an amino-terminal PH domain, a central PTB domain and numerous potential sites of tyrosine phosphorylation. Tyrosine phosphorylation of p56Dok-2 occurs upon stimulation of cells with a variety of stimuli or in cells transformed by oncogenic tyrosine kinases such as v-Src and Bcr-Abl (3–5). Very little is known about p56Dok-2 function and the role of phosphorylation in the modulation of these functions. Based on the presence of several signaling domains (PH, PTB domain, tyrosine residue and proline-rich regions), it has been proposed that they act as docking proteins that link RTKs to signal transduction pathways. p56Dok-2 has been proposed to be a negative regulator of cytokine-induced proliferation in T cells (5). It was demonstrated that phosphorylated Tyr351 mediates an association with the SH2 domain of Nck (4).
Signals from most growth factors and cytokines are transduced by receptor tyrosine kinases or non-receptor tyrosine kinases. Activated tyrosine kinases phosphorylate their substrates, which mediate the cellular response to extracellular stimuli. A long-sought major substrate termed p62dok (downstream of tyrosine kinase) for many tyrosine kinases including c-kit, v-abl, v-Fps, v-Src, v-Fms, and activated EGF, PDGF, IGF, VEGF and insulin receptors was identified recently from human and mouse by several laboratories. Upon phosphorylation, p62dok forms a complex with the ras GTPase-activating protein (RasGAP). p62dok represents a new family with very recently identified p56dok. Human DOK1 is a 481 amino acid protein.
Applications
Suitable for use in Western Blot. Other applications not tested.
Recommended Dilution
Western Blot: 1:1000 Optimal dilutions to be determined by the researcher.
Storage and Stability
May be stored at 4°C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Aliquots are stable for 12 months after receipt. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.
Immunogen
Synthetic phospho-peptide corresponding to residues surrounding tyrosine 351 of mouse p56Dok-2. Uniprot/Swiss Accession: O60496
Form
Supplied as a liquid in 10mM sodium HEPES, pH 7.5, 150mM sodium chloride, 0.1mg/ml BSA, 50% glycerol
Purity
Purified by Protein A and peptide affinity chromatography.
Specificity
Recognizes endogenous levels of p56Dok-2 only when phosphorylated at tyrosine 351. Does not crossreact with other tyrosine phosphorylated p62Dok family members.