Phospho-(Ser) Kinase Substrate Antibody Sampler Kit

Background

Phospho-(Ser) kinases and phosphatases play critical roles in a wide range of biological processes. Each phospho-(Ser) kinase phosphorylates serine within a specific motif. The MAPK and CDK families of serine protein kinases phosphorylate serine followed by proline residue (1-3). The consensus amino acid sequence for CDK substrate is (K/R)(S*)PX(K/R), where X denotes any one of the 20 amino acids and S* is the phosphorylation site (4-6). MAPK phosphorylates substrates with the concensus sequence PX(S*)P. The 14-3-3 proteins are a highly conserved family of proteins involved in the regulation of cell survival, apoptosis, proliferation and checkpoint control (7-11). Binding of 14-3-3 is mediated through phospho-serine-containing proteins (12). Two different phospho-serine containing motifs are found using a degenerate phospho-serine-oriented peptide library technique, RSXS*XP and RXY/FXS*XP (12). Motif 1 (Arg/Lys and Ser at positions -3 and -2, phospho-Ser at position 0, and Pro at position +2) is found in critical regulatory proteins including Bad, cdc25C, FoxO3A, PKC and c-Raf (11, 13). Motif 2 (RXY/FXS*XP) is found in critical regulatory proteins including cdc25A, cdc25B, PKCγ, IRS-1 and BCR (12). Although Phospho-(Ser) Arg-X-Tyr/Phe-X-pSer Motif Antibody binds 14-3-3 binding motif 2 with no requirement for proline in the +2 position, it provides a powerful tool for the discovery and characterization of potential 14-3-3 binding motif 2-containing proteins or other proteins with the RXY/FXS* motif. Antibodies specific to particular kinase substrates are invaluable reagents in determining kinase activity and identifying potential new kinase substrates. CST has developed antibodies that recognize phosphorylated serine within the context of a protein motif that is phosphorylated by MAPK/CDK, CDKs or 14-3-3. As shown by DELFIA or ELISA, each phospho-(Ser) kinase substrate antibody in this sampler kit is specific to its kinase substrate motif.