Kinase Substrate, phosphorylated (Ser/Thr) BioAssay™ Sample Kit

Phospho-(Ser/Thr) kinases and phosphatases play critical roles in a wide range of biological processes. Each phospho-(Ser/Thr) kinase phosphorylates serine or threonine within a specific motif. Akt phosphorylates substrates at a serine or threonine only in a conserved motif characterized by arginine at positions –5 and –3 (1). Conventional PKC isozymes phosphorylate substrates containing serine or threonine, with arginine or lysine at the –3, –2 and +2 positions, and a hydrophobic amino acid at position +1 (2,3). A consensus phosphorylation site of PKA is serine or threonine with arginine at the –2 and –3 positions (3). The MAPK and CDK families of serine/threonine protein kinases phosphorylate threonine or serine followed by proline residue (3–5). PDK1 has been shown to phosphorylate the T-loop of many members of the AGC subfamily of protein kinases in a sequence motif comprising T*FCGT, where the first threonine residue becomes phosphorylated by PDK1 (6). ATM and the related kinase ATR phosphorylate serine or threonine in an S*/T*Q motif (7,8) Antibodies specific to particular kinase substrates are invaluable reagents in determining kinase activity and identifying potential new kinase substrates. We have antibodies that recognize phosphorylated serine or threonine within the context of a protein motif that is phosphorylated by Akt, PKC, PKA, MAPK/CDK, PDK1 or ATM/ATR. As shown by ELISA, each phospho-(Ser/Thr) kinase substrate antibody in this sampler kit is specific to its kinase substrate motif.