Phospho-Threonine-X-Arginine Antibody detects endogenous levels of proteins containing the phospho-Thr-X-Arg motif. This antibody detects phosphorylated Thr followed by Arg or Lys at the +2 position, though its reactivity is lower for Lys compared to Arg at the +2 position. The antibody does not cross-react with nonphospho-Thr or phospho-Ser in the same motif. It recognizes phospho-Thr in the FFT*R motif in PKCbeta II but does not recognize phospho-Thr in other motifs that lack Lys or Arg at +2. (U.S. Patent No's.: 6,441,140; 6,982,318; 7,259,022; 7,344,714; U.S.S.N. 11,484,485; and all foreign equivalents.)
Source / Purification
Polyclonal antibodies are produced by immunizing animals with a synthetic peptide containing the phospho-Thr-X-Arg motif. Antibodies are purified by protein A and peptide affinity chromatography.
Background
Some signaling molecules can be regulated by phosphorylation at a specific threonine followed by arginine or lysine at the +2 position. For example, conventional PKC isozymes phosphorylate substrates containing serine or threonine with Arg or Lys at the -3, -2 and +2 positions (1-2). c-Raf, a mitogen-activated protein kinase and the main effector recruited by GTP-bound Ras, is phosphorylated at Thr481 and Thr491 followed by Lys at the +2 position (3). Phosphorylation of these sites is important for enzyme activities. To determine the phosphorylation state of Thr in the Thr-X-Arg motif, and to identify potential new phosphorylation sites with this motif, Cell Signaling Technology has developed a Phospho-Threonine X-Arginine Antibody that recognizes phosphorylated Thr followed by Arg or Lys at the +2 position.