The Phospho-(Ser/Thr) Kinase Substrate Antibody Sampler Kit provides an economical means to investigate the downstream activity of select serine/threonine kinases. The kit contains enough primary antibody to perform two western blot experiments with each antibody.

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). AMPK phosphorylates consensus motif (L/M)XRXX(S/T)XXXL (6). Antibodies recognizing the LXRXX(S/T) motif are very useful in the identification of AMPK substrates. The consensus amino acid sequence for CDK substrate is (K/R)(S*)PX(K/R), where denotes any one of the 20 amino acids and S* is the phosphorylation site (4-6). 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. CST has developed antibodies that recognize phosphorylated serine or threonine within the context of a protein motif that is phosphorylated by Akt, PKC, PKA, MAPK/CDK, CDKs or ATM/ATR. As shown by peptide pairing ELISA, each phospho-(Ser/Thr) kinase substrate antibody in this sampler kit is specific to its kinase substrate motif.