LKBtide; LKB1/STK11 Substrate Peptide

Product Name: LKBtide; LKB1/STK11 Substrate Peptide

Sequence One Letter Code: LSNLYHQGKFLQTFCGSPLYRRR

Sequence Three Letter Code: H-Leu-Ser-Asn-Leu-Tyr-His-Gln-Gly-Lys-Phe-Leu-Gln-Thr-Phe-Cys-Gly-Ser-Pro-Leu-Tyr-Arg-Arg-Arg-OH

Chemical Formula:C126H194N38O32S1

Molecular Weight: 2785.4

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: Cancer Disease Research

Conjugation: Unconjugated

Code Nacres: NA.26

Application: LKBtide is a synthetic peptide substrate selectively phosphorylated by serine/threonine kinase 11 (STK11), also known as LKB1. The sequence is derived from sucrose non-fermenting 1 (SNF1) kinase, a component of the conserved LKB1–AMPK signaling pathway. LKB1 functions as a master regulator of cellular energy homeostasis, metabolic stress responses, and tumor suppression. LKBtide is widely employed in in vitro kinase assays to quantify LKB1 catalytic activity, determine enzyme kinetics, and evaluate ATP-dependent phosphorylation efficiency. It is also suitable for screening small-molecule modulators targeting LKB1-mediated signaling. As a defined and reproducible substrate, LKBtide supports mechanistic studies of AMPK pathway regulation and is broadly applied in metabolic research, oncology, and investigations of energy-sensing kinase networks.

Current Research: The LKB1–AMPK signaling pathway is a central regulator of cellular energy homeostasis and metabolic stress responses. Serine/threonine kinase 11 (STK11), also known as LKB1, functions as an upstream kinase that activates AMP-activated protein kinase (AMPK) and a family of related kinases involved in controlling metabolism, cell polarity, and growth. LKB1 has also been identified as a tumor suppressor, with mutations in the STK11 gene linked to several diseases, including Peutz–Jeghers syndrome and multiple types of cancer such as lung adenocarcinoma. Because of its central role in energy sensing and metabolic regulation, accurate measurement of LKB1 activity is critical for understanding how cells respond to metabolic stress. The synthetic peptide LKBtide has become a widely used substrate for studying the catalytic activity of LKB1 and investigating the molecular mechanisms of the LKB1–AMPK signaling axis. One major application of LKBtide is in in vitro kinase assays designed to quantify LKB1 activity. The peptide sequence is derived from SNF1 kinase, the yeast ortholog of AMPK, which shares structural and functional similarities with mammalian AMPK. In biochemical assays, purified LKB1 phosphorylates LKBtide in the presence of ATP, allowing researchers to measure enzyme activity through radiometric assays, phospho-specific detection methods, or mass spectrometry. Because the peptide substrate is structurally defined and highly reproducible, it provides a reliable readout for evaluating ATP-dependent phosphorylation kinetics and enzyme efficiency. Current research frequently employs LKBtide to investigate the regulation of LKB1 catalytic activity under metabolic stress conditions. In response to changes in cellular energy status—such as increased AMP or ADP levels—AMPK signaling becomes activated to restore metabolic balance by promoting catabolic pathways and inhibiting energy-consuming processes. By monitoring LKB1-mediated phosphorylation of LKBtide, researchers can assess how upstream regulatory factors, cofactors, or interacting proteins influence the activation of the LKB1 kinase complex. These studies contribute to a deeper understanding of how cells sense and adapt to fluctuations in energy availability. Another important area of research involves screening small-molecule modulators of LKB1 signaling. Because dysregulation of the LKB1–AMPK pathway has been implicated in metabolic disorders and cancer, identifying compounds that influence LKB1 activity has become an active field of drug discovery. LKBtide-based kinase assays provide a convenient platform for evaluating candidate molecules that may enhance or inhibit LKB1-mediated phosphorylation. High-throughput screening approaches often rely on peptide substrates such as LKBtide to quantify enzyme activity in the presence of potential modulators. LKBtide is also used to explore mechanistic aspects of tumor suppression mediated by LKB1. Loss of LKB1 function can disrupt cellular metabolic control and contribute to uncontrolled proliferation. In experimental systems, kinase assays using LKBtide allow investigators to compare the catalytic activity of wild-type LKB1 with that of disease-associated mutants. These studies help determine how specific mutations impair enzyme function and alter downstream signaling pathways involved in growth regulation and metabolic adaptation. Recent research has further expanded the use of LKBtide in studies examining the broader network of AMPK-related kinases. LKB1 activates not only AMPK but also several related kinases involved in processes such as cell polarity, cytoskeletal organization, and stress responses. By monitoring phosphorylation of LKBtide in controlled biochemical assays, researchers can investigate how different components of the LKB1 signaling complex contribute to kinase activation and substrate recognition. In metabolic research, the peptide is frequently used to evaluate how nutrient availability, mitochondrial function, and cellular stress influence kinase activity. Because the LKB1–AMPK pathway plays a key role in regulating glucose metabolism, lipid oxidation, and autophagy, measuring LKB1 activity with defined substrates provides valuable insights into metabolic adaptation mechanisms in both normal and disease contexts. In summary, LKBtide is a well-established peptide substrate widely used to study the enzymatic activity of the tumor suppressor kinase LKB1. Its defined sequence and reliable phosphorylation properties make it an essential reagent for kinase activity assays, enzyme kinetics analysis, and drug discovery studies targeting the LKB1–AMPK signaling pathway. Through these applications, LKBtide continues to support research into metabolic regulation, cellular energy sensing, and the molecular mechanisms linking metabolism to cancer and other diseases.