Phospho-RAF1 (S289) Antibody
Description
Definition and Target Specificity
Phospho-RAF1 (S289) Antibody is a rabbit-derived polyclonal antibody targeting the phosphorylated serine 289 residue of the RAF1 protein (UniProt ID P04049). This antibody is validated for immunohistochemistry (IHC-P) in human samples and recognizes the synthetic peptide immunogen corresponding to the phosphorylated S289 epitope .
Biological Context of RAF1 S289 Phosphorylation
RAF1 (C-Raf) is a serine/threonine kinase central to the Ras-Raf-MEK-ERK signaling pathway. Phosphorylation at S289 is part of a regulatory feedback mechanism:
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Inactivation Mechanism: S289 phosphorylation by MAPK1/ERK2 contributes to RAF1 inactivation, forming a negative feedback loop to modulate pathway activity .
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Cellular Implications: This modification is linked to cell fate decisions, including apoptosis, proliferation, and oncogenic transformation .
Oncogenic Transformation Studies
The antibody has been used to investigate RAF1’s role in epithelial-mesenchymal transition (EMT) via repression of occludin (OCLN). Phosphorylated RAF1 upregulates SNAI2/SLUG, a transcriptional repressor of OCLN, promoting tumor invasiveness .
Apoptosis Regulation
Phospho-RAF1 (S289) is implicated in mitochondrial apoptosis pathways. Active RAF1 translocates to mitochondria, binds BCL2, and displaces pro-apoptotic BAD, thereby inhibiting caspase activation .
Technical Validation and Performance
Phosphorylation Network and Cross-Regulation
Phospho-RAF1 (S289) exists within a dynamic signaling network:
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Interacting Kinases: PAK1 (activates RAF1 via S338/S339 phosphorylation), MAPK1/ERK2 (inactivates via S289/S296/S301 phosphorylation) .
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Methylation Sensitivity: S289 phosphorylation levels are influenced by cellular methylation potential. Inhibitors like 5'-methylthioadenosine (MTA) alter phosphorylation patterns under HGF stimulation .
