Phospho-RelB (Ser552) Antibody (Rabbit mAb) [C17L2]

Application: Reactivity: Human, Mouse

Usage Information

Dilution
WB1:1000 IP1:100 IF1:400 FCM1:400 - 1:1600

Application
WB, IP, IF, FCM

Reactivity
Human, Mouse

Source
Rabbit Monoclonal Antibody

Storage Buffer
PBS, pH 7.2+50% Glycerol+0.05% BSA+0.01% NaN3

Storage (from the date of receipt)
-20°C (avoid freeze-thaw cycles), 2 years

Predicted MW
62 kDa

Datasheet & SDS

Biological Description

Specificity
Phospho-RelB (Ser552) Antibody (Rabbit mAb) [C17L2] detects endogenous levels of RelB only when phosphorylated at Ser552.

Clone
C17L2

Synonym(s)
I-Rel; IMD53; IREL; REL-B; RELB; RELB proto-oncogene, NF-kB subunit; v-rel reticuloendotheliosis viral oncogene homolog B

Background
RelB is a member of the NF‑κB/Rel transcription factor family that contains an N‑terminal Rel homology domain supporting DNA binding, dimerization with p50 or p52 and nuclear localization, together with a unique N‑terminal leucine zipper and extended transactivation region that confer distinctive roles in lymphoid development, dendritic cell biology and non‑canonical NF‑κB signaling, and phosphorylation of RelB at Ser552 defines a post‑translationally modified state that controls its stability and transcriptional output. The protein is held inactive in the cytoplasm in complex with the p100 precursor of NF‑κB2, which functions as a RelB inhibitor and sequesters RelB until signals activating the non‑canonical NF‑κB pathway, such as BAFF‑R or CD40 engagement, induce NIK and IKKα‑dependent phosphorylation and partial proteasomal processing of p100 to p52, allowing RelB–p52 heterodimers to accumulate and translocate to chromatin where they regulate genes involved in secondary lymphoid organ formation, dendritic cell maturation and immunoregulatory cytokine production. RelB is also subject to signal‑induced turnover distinct from IκB regulation: T‑cell receptor or TPA/ionomycin stimulation causes rapid phosphorylation of RelB at Thr84 and Ser552, followed by an N‑terminal cleavage and complete proteasomal degradation; mutation of Thr84 and Ser552 to non‑phosphoacceptor residues abolishes this phosphorylation and stabilizes RelB, demonstrating that site‑specific phosphorylation at Ser552 is a necessary prerequisite for RelB proteolysis and serves as a mechanism to reset NF‑κB‑dependent gene expression programs after activation. Glycogen synthase kinase‑3β directly mediates phosphorylation of RelB at Ser552 (Ser573 in human numbering) and forms a complex with RelB, and inhibition of GSK3β blocks Ser552 phosphorylation and RelB degradation, identifying GSK3β–Ser552 as a key axis linking broader metabolic and stress signaling to NF‑κB subunit composition and duration of RelB‑dependent transcription. In contrast, phosphorylation of RelB at Ser368 allows its association with and stabilization by p100, showing that distinct phosphorylation sites on RelB differentially control its interaction with inhibitors, chromatin and the proteasome, and that Ser552 phosphorylation specifically directs RelB away from the p100‑stabilized pool toward degradation. RelB generally binds DNA as a heterodimer with p50 or p52, and RelB/p50 or RelB/p52 complexes bind κB sites with affinities comparable to classical NF‑κB but can both activate euchromatin and enforce facultative heterochromatin at defined promoters, giving RelB a dual role as transcriptional activator and repressor that is shaped by its post‑translational modification status, including phosphorylation at Ser552. In immune and inflammatory contexts, RelB is required to repress immediate‑response pro‑inflammatory genes during endotoxin tolerance and to limit excessive NF‑κB activity, and post‑translational modifications including Ser552 phosphorylation modulate these functions by influencing RelB’s residence time on chromatin and its ability to maintain repressive heterochromatin at specific loci. Dysregulation of RelB and its phosphorylation has been implicated in B‑cell lymphomagenesis and chronic inflammatory conditions: RelB contributes to survival, migration and lymphomagenesis of B cells with constitutively active CD40 signaling, and altered control of RelB turnover through Ser552 phosphorylation and GSK3β activity affects the balance between canonical and non‑canonical NF‑κB outputs that support malignant B‑cell proliferation and tissue invasion.

Background

RelB is a member of the NF‑κB/Rel transcription factor family that contains an N‑terminal Rel homology domain supporting DNA binding, dimerization with p50 or p52 and nuclear localization, together with a unique N‑terminal leucine zipper and extended transactivation region that confer distinctive roles in lymphoid development, dendritic cell biology and non‑canonical NF‑κB signaling, and phosphorylation of RelB at Ser552 defines a post‑translationally modified state that controls its stability and transcriptional output. The protein is held inactive in the cytoplasm in complex with the p100 precursor of NF‑κB2, which functions as a RelB inhibitor and sequesters RelB until signals activating the non‑canonical NF‑κB pathway, such as BAFF‑R or CD40 engagement, induce NIK and IKKα‑dependent phosphorylation and partial proteasomal processing of p100 to p52, allowing RelB–p52 heterodimers to accumulate and translocate to chromatin where they regulate genes involved in secondary lymphoid organ formation, dendritic cell maturation and immunoregulatory cytokine production. RelB is also subject to signal‑induced turnover distinct from IκB regulation: T‑cell receptor or TPA/ionomycin stimulation causes rapid phosphorylation of RelB at Thr84 and Ser552, followed by an N‑terminal cleavage and complete proteasomal degradation; mutation of Thr84 and Ser552 to non‑phosphoacceptor residues abolishes this phosphorylation and stabilizes RelB, demonstrating that site‑specific phosphorylation at Ser552 is a necessary prerequisite for RelB proteolysis and serves as a mechanism to reset NF‑κB‑dependent gene expression programs after activation. Glycogen synthase kinase‑3β directly mediates phosphorylation of RelB at Ser552 (Ser573 in human numbering) and forms a complex with RelB, and inhibition of GSK3β blocks Ser552 phosphorylation and RelB degradation, identifying GSK3β–Ser552 as a key axis linking broader metabolic and stress signaling to NF‑κB subunit composition and duration of RelB‑dependent transcription. In contrast, phosphorylation of RelB at Ser368 allows its association with and stabilization by p100, showing that distinct phosphorylation sites on RelB differentially control its interaction with inhibitors, chromatin and the proteasome, and that Ser552 phosphorylation specifically directs RelB away from the p100‑stabilized pool toward degradation. RelB generally binds DNA as a heterodimer with p50 or p52, and RelB/p50 or RelB/p52 complexes bind κB sites with affinities comparable to classical NF‑κB but can both activate euchromatin and enforce facultative heterochromatin at defined promoters, giving RelB a dual role as transcriptional activator and repressor that is shaped by its post‑translational modification status, including phosphorylation at Ser552. In immune and inflammatory contexts, RelB is required to repress immediate‑response pro‑inflammatory genes during endotoxin tolerance and to limit excessive NF‑κB activity, and post‑translational modifications including Ser552 phosphorylation modulate these functions by influencing RelB’s residence time on chromatin and its ability to maintain repressive heterochromatin at specific loci. Dysregulation of RelB and its phosphorylation has been implicated in B‑cell lymphomagenesis and chronic inflammatory conditions: RelB contributes to survival, migration and lymphomagenesis of B cells with constitutively active CD40 signaling, and altered control of RelB turnover through Ser552 phosphorylation and GSK3β activity affects the balance between canonical and non‑canonical NF‑κB outputs that support malignant B‑cell proliferation and tissue invasion.

References
https://pubmed.ncbi.nlm.nih.gov/27153093/ https://pubmed.ncbi.nlm.nih.gov/11781828/

Protein Size (kDa)	PVDF Transfer Membrane Pore Size (μm)
< 10	0.22
10-20	0.22
20-30	0.45
30-45	0.45
45-70	0.45
80-100	0.45
100-140	0.45
> 140	0.45

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Protein Size (kDa)	Separating Gel Percentage
4-40	20%
12-45	15%
10-70	12.5%
15-100	10%
25-100	8%
60-210	5%