B-Raf (S446) [C-Raf (S338) /A-Raf (S299) ], Phosphospecific Antibody

The Ras-Raf-MAP kinase signaling pathway is involved in control of cell proliferation and differentiation. The Raf kinase family includes A-Raf, B-Raf, and C-Raf. Each family member has three highly conserved regions (CR1-3) . The N-terminal CR1 contains the Ras-GTP-binding domain. The CR2 contains a negative regulatory serine residue (C-Raf (S259) /B-Raf (S365) ) that may bind 14-3-3 proteins. The CR3 is the catalytic domain that contains phosphorylation sites for Raf-regulating enzymes within two segments, the N-region and the activation segment. Activation of C-Raf involves phosphorylation at many sites including Ser-338, Tyr-341, and multiple catalytic domain sites. In B-Raf, multiple phosphorylation sites have been identified, but their specific roles are uncertain. Phosphorylation of Ser-446 may prime B-Raf for activation, and Ser-446 and/or Ser-447 phosphorylation may be critical for B-Raf biological activity during PC12 differentiation. Ser-579 is required for growth factor activation and kinase activity. Thus, multiple sites of phosphorylation within Rafs may be important for regulation of their activity.

This antibody was cross-adsorbed to phospho-B-Raf (Ser-579) peptide before affinity purification using phospho-B-Raf (Ser-446) peptide. The purified antibody detects a strong band at 95 kDa* and a weaker band at 105 kDa in western blots of human Jurkat or A431 cells treated with Calyculin A.