Catalog # IP1031

IκBα (Tyr-42), phospho-specific Antibody

Rabbit Polyclonal

Application / Dilution

Size 100 μl

Species Reactivity Hu, Rt, Ms

MW 38 kDa



The NF-κB/Rel transcription factors are present in the cytosol in an inactive state complexed with the inhibitory IκB proteins. Activation of IκBα occurs through both serine and tyrosine phosphorylation events. Activation through phosphorylation at Ser-32 and Ser-36 is followed by proteasome-mediated degradation, resulting in the release and nuclear translocation of active NF-κB. This pathway of IκBα regulation occurs in response to various NF-κB-activating agents, such as TNFα, interleukins, LPS, and irradiation. An alternative pathway for IκBα regulation occurs through tyrosine phosphorylation of Tyr-42 and Tyr-305. Tyr-42 is phosphorylated in response to oxidative stress and growth factors. This phosphorylation can lead to degradation of IκBα and NF-κB-activation. In contrast, Tyr-305 phosphorylation by c-Abl has been implicated in IκBα nuclear translocation and inhibition of NF-κB-activation. Thus, tyrosine phosphorylation of IκBα may be an important regulatory mechanism in NF-κB signaling.



Waris et al. (2003) J Biol Chem 278(42):40778.
Bui, N.T. et al. (2001) J Cell Biol 152(4):753.

Western blot analysis of A431 cells treated with pervanadate (1 mM) for 30 min. Blots were probed with anti-IκBα (lane 1), anti-IκBα (Tyr-42) (IP1031; lanes 2-5), or anti-IκBα (Tyr-305) (IP1041; lanes 6-9). In some lanes, the antibodies were used in the absence (lane 2 & 6) or presence of IκBα (Tyr-42) (lane 3 & 8) or IκBα (Tyr-305) (lane 4 & 7) blocking peptides, or BSA conjugated to phospho-tyrosine (lane 5 & 9).

IκBα (Tyr-42) synthetic peptide (coupled to KLH) corresponding to amino acid residues around tyrosine 42 of human IκBα. This peptide sequence has low homology to other IκB proteins, but does have some homology to unrelated proteins that may have a conserved tyrosine phosphorylation motif.

*For more information, see UniProt Accession P25963
Rabbit polyclonal, affinity-purified antibody is supplied in 100µl phosphate-buffered saline, 50% glycerol, 1 mg/ml BSA, and 0.05% sodium azide. Store at –20°C. Stable for 1 year.

The products are are safely shipped at ambient temperature for both domestic and international shipments. Each product is guaranteed to match the specifications as indicated on the corresponding technical data sheet. Please store at -20C upon arrival for long term storage.

This antibody was cross-adsorbed to phospho-tyrosine coupled to agarose then affinity purified using phospho-IκBα (Tyr-42) peptide (without carrier). The antibody detects a 38 kDa* protein on SDS-PAGE immunoblots of A431 and Jurkat cells treated with pervanadate, but not in control cells. Due to homologies to tyrosine sites on other proteins, it is recommended that the antibody be used to detect phosphorylation of immunoprecipitated IκBα.

*All molecular weights (MW) are confirmed by comparison to Bio-Rad Rainbow Markers and to western blot mobilities of known proteins with similar MW.

This kit contains: