Phospho-LKB1 (Ser428) Antibody [H12K23]

Application: Reactivity: Human, Mouse, Rat, Monkey

Lane 1: L929, Lane 2: L929 (TPA and UV treated), Lane 3: COS-7, Lane 4: COS-7 (TPA and UV treated)

Usage Information

Dilution
WB1:1000

Application
WB

Reactivity
Human, Mouse, Rat, Monkey

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
54 kDa

Positive Control	Caki cells (TPA and UV treated); L929 cells (TPA and UV treated); COS cells (TPA and UV treated); NBT-II cells (TPA and UV treated)
Negative Control	Caki cells; NBT-II cells

Datasheet & SDS

Biological Description

Specificity
Phospho-LKB1 (Ser428) Antibody [H12K23] detects endogenous levels of total LKB1 protein only when it is phosphorylated at Ser428.

Clone
H12K23

Synonym(s)
STK11; Serine/threonine-protein kinase STK11; EC:2.7.11.1; Liver kinase B1 (LKB1; hLKB1); Renal carcinoma antigen NY-REN-19; LKB1; PJS.

Background
Phospho-LKB1 (Ser428) represents the activated form of the serine/threonine tumor suppressor kinase LKB1 (STK11), which forms a heterotrimeric complex with STRADα/β and MO25 to phosphorylate and activate AMPK at Thr172 and related kinases, maintaining cellular polarity, energy homeostasis, and growth control. LKB1 contains an N-terminal nuclear localization domain, a central kinase domain with a conserved ATP-binding lysine and activation loop motifs, and a C-terminal non-kinase region that includes Ser428 within a PKCζ consensus site alongside regulatory residues such as Ser325 and Thr363. Flexible loops facilitate the binding of pseudokinase STRAD, enabling allosteric activation. Phosphorylation of Ser428 by PKCζ, in response to signals like metformin treatment, oxidative stress, or energy depletion, triggers export of LKB1 from the nucleus to the cytosol, enhances the stability of the STRAD/MO25 complex, increases catalytic activity, and promotes robust AMPK Thr172 phosphorylation, thereby driving catabolic metabolism, autophagy, and inhibition of mTORC1 and GSK3β. This modification relieves nuclear retention, facilitates LKB1-AMPK docking, suppresses Akt signaling via PTEN stabilization, and fine-tunes apoptotic responses under nutrient stress. Mutation of Ser428 to alanine blocks LKB1 translocation, abolishes metformin-enhanced AMPK activation, and impairs downstream polarity signaling via MARKs and Sad kinases. Dysregulation of LKB1 Ser428 phosphorylation is implicated in diseases such as Peutz-Jeghers syndrome and various cancers, including lung cancer and melanoma, by disrupting energy sensing and growth control, while hyperactivation is associated with endothelial dysfunction in diabetes, and hypoactivation promotes tumorigenesis through unchecked cell proliferation.

Background

Phospho-LKB1 (Ser428) represents the activated form of the serine/threonine tumor suppressor kinase LKB1 (STK11), which forms a heterotrimeric complex with STRADα/β and MO25 to phosphorylate and activate AMPK at Thr172 and related kinases, maintaining cellular polarity, energy homeostasis, and growth control. LKB1 contains an N-terminal nuclear localization domain, a central kinase domain with a conserved ATP-binding lysine and activation loop motifs, and a C-terminal non-kinase region that includes Ser428 within a PKCζ consensus site alongside regulatory residues such as Ser325 and Thr363. Flexible loops facilitate the binding of pseudokinase STRAD, enabling allosteric activation. Phosphorylation of Ser428 by PKCζ, in response to signals like metformin treatment, oxidative stress, or energy depletion, triggers export of LKB1 from the nucleus to the cytosol, enhances the stability of the STRAD/MO25 complex, increases catalytic activity, and promotes robust AMPK Thr172 phosphorylation, thereby driving catabolic metabolism, autophagy, and inhibition of mTORC1 and GSK3β. This modification relieves nuclear retention, facilitates LKB1-AMPK docking, suppresses Akt signaling via PTEN stabilization, and fine-tunes apoptotic responses under nutrient stress. Mutation of Ser428 to alanine blocks LKB1 translocation, abolishes metformin-enhanced AMPK activation, and impairs downstream polarity signaling via MARKs and Sad kinases. Dysregulation of LKB1 Ser428 phosphorylation is implicated in diseases such as Peutz-Jeghers syndrome and various cancers, including lung cancer and melanoma, by disrupting energy sensing and growth control, while hyperactivation is associated with endothelial dysfunction in diabetes, and hypoactivation promotes tumorigenesis through unchecked cell proliferation.

References
https://pubmed.ncbi.nlm.nih.gov/18250273/ https://pubmed.ncbi.nlm.nih.gov/19274086/

Reference Table for Selecting PVDF Membrane Pore Size Specifications

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%