Srctide [GEEPLYWSFPAKKK-NH2], FAM labeled

Product Name: Srctide [GEEPLYWSFPAKKK-NH2], FAM labeled

Sequence One Letter Code: 5-FAM-GEEPLYWSFPAKKK-NH2

Sequence Three Letter Code: 5-FAM-Gly-Glu-Glu-Pro-Leu-Tyr-Trp-Ser-Phe-Pro-Ala-Lys-Lys-Lys-NH2

Chemical Formula:C102H129N19O26

Molecular Weight: 2037.3

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C Protected from light

Research Area: Cancer Disease Research

Source / Species: Synthetic construct

Conjugation: Conjugated

Conjugation Type: Fluorescent dyes

Code Nacres: NA.26

Application: This peptide is a fluorescently labeled derivative of Srctide that carries an N-terminal 5-carboxyfluorescein (5-FAM) tag, enabling sensitive fluorescence-based detection in kinase activity assays. Srctide itself is a broadly recognized substrate for numerous protein kinases, including Src family kinases, receptor tyrosine kinases, and Tec family kinases involved in signal transduction pathways. The FAM label allows convenient monitoring of phosphorylation events using fluorescence-based detection methods, supporting both real-time kinetic measurements and endpoint assay formats. Because of its strong signal output and compatibility with microplate-based detection systems, this peptide is particularly useful for high-throughput screening applications. It can be used to measure kinase activity, evaluate inhibitor potency, and compare substrate preferences across different kinase families. The peptide therefore serves as a practical tool for signaling research, kinase profiling, and pharmacological studies targeting kinase-regulated pathways in cancer and cell biology.

Current Research: Protein phosphorylation is one of the most important regulatory mechanisms in cellular signaling. Protein kinases catalyze the transfer of phosphate groups from ATP to specific amino acid residues on target proteins, thereby controlling processes such as cell growth, differentiation, migration, and survival. Because dysregulation of kinase activity is frequently associated with diseases such as cancer and inflammatory disorders, accurate methods for measuring kinase activity are essential in biochemical and pharmacological research. One widely used experimental tool is Srctide, a synthetic peptide substrate recognized by multiple kinases. When combined with a fluorescent tag such as 5-carboxyfluorescein (5-FAM), this substrate becomes a powerful reagent for fluorescence-based kinase assays. Srctide as a Broad-Spectrum Kinase Substrate Srctide was originally designed as a peptide substrate for Src family kinases, a group of non-receptor tyrosine kinases involved in many signal transduction pathways. Members of the Src family—including Src, Fyn, Lyn, and Yes—play important roles in regulating cell adhesion, proliferation, immune responses, and cytoskeletal organization. Because these kinases interact with receptor tyrosine kinases and other signaling molecules, they function as key intermediates in cellular communication networks. The peptide sequence of Srctide contains a phosphorylation motif that is efficiently recognized by Src kinases. However, its usefulness extends beyond this family. The peptide can also be phosphorylated by several receptor tyrosine kinases and other cytoplasmic kinases, including members of the Tec kinase family. This broad compatibility has made Srctide a convenient substrate for evaluating kinase activity across a variety of signaling pathways. Fluorescent Labeling with 5-Carboxyfluorescein (FAM) To enhance detection sensitivity and enable fluorescence-based assay formats, Srctide can be modified with an N-terminal 5-carboxyfluorescein (5-FAM) fluorophore. FAM is a widely used fluorescent dye characterized by strong signal intensity, good photostability, and compatibility with standard fluorescence detection instruments. The presence of the fluorescent tag allows phosphorylation reactions involving the peptide to be detected using fluorescence-based readouts, eliminating the need for radioactive labeling methods that were traditionally used in kinase assays. This approach simplifies experimental workflows and improves safety in laboratory environments. In addition, fluorescence detection supports both real-time kinetic monitoring and endpoint assay measurements, providing flexibility in experimental design. Monitoring Kinase Activity Using Fluorescent Substrates In a typical kinase assay, purified kinase enzyme is incubated with ATP and the FAM-labeled Srctide substrate. As the kinase transfers a phosphate group to the peptide, the phosphorylation event can be detected using fluorescence-based analytical methods. Depending on the assay format, changes in fluorescence polarization, mobility shifts, or fluorescence resonance measurements may be used to quantify phosphorylation. Because the fluorescent signal is strong and easily measured, the assay allows researchers to determine enzyme activity, reaction rates, and catalytic efficiency. Such measurements are essential for understanding how kinases regulate signaling pathways and how their activity is modulated by interacting proteins or cellular conditions. High-Throughput Screening for Kinase Inhibitors One of the most important applications of fluorescent peptide substrates is in high-throughput screening (HTS) for kinase inhibitors. Many therapeutic drugs, particularly anticancer agents, are designed to target dysregulated kinase signaling pathways. Screening large libraries of chemical compounds requires assay systems that are both sensitive and compatible with automated detection platforms. The strong fluorescence signal generated by FAM-Srctide makes it particularly well suited for microplate-based assays used in HTS workflows. Researchers can rapidly measure phosphorylation levels across hundreds or thousands of samples, enabling efficient identification of compounds that inhibit kinase activity. By comparing phosphorylation levels in the presence and absence of candidate inhibitors, scientists can determine inhibitor potency and dose–response relationships, supporting early-stage drug discovery efforts. Investigating Kinase Substrate Specificity Another advantage of FAM-Srctide is its usefulness in studying kinase substrate recognition and specificity. Because the peptide can be phosphorylated by multiple kinase families, it provides a convenient platform for comparing enzymatic activity across different kinases. Researchers can evaluate how structural changes in kinases—such as mutations within catalytic domains—affect substrate phosphorylation. These studies help reveal how kinases recognize target sequences and how signaling networks maintain specificity despite overlapping substrate preferences. Such mechanistic insights are particularly important for understanding oncogenic kinase activation, where mutations often alter kinase catalytic behavior. Applications in Signaling and Cancer Research Kinases play central roles in pathways that regulate cell proliferation, migration, and survival, processes that are frequently altered in cancer. Tools that allow accurate measurement of kinase activity are therefore essential for studying how signaling pathways become dysregulated in disease. The FAM-labeled Srctide substrate is widely used in experiments investigating Src kinase signaling, receptor-mediated signal transduction, and oncogenic kinase networks. Its compatibility with fluorescence-based assays allows researchers to analyze kinase activity efficiently in biochemical systems. A Practical Tool for Kinase Profiling The FAM-Srctide peptide substrate combines the broad kinase compatibility of Srctide with the sensitivity of fluorescence detection. The N-terminal 5-FAM label enables convenient monitoring of phosphorylation events, supporting both real-time kinetic analysis and high-throughput experimental formats. Because of its strong fluorescence signal and versatility in assay design, this peptide serves as a practical tool for kinase activity measurement, inhibitor screening, and substrate profiling. Its continued use in signaling research and pharmacological studies contributes to a deeper understanding of kinase-regulated cellular pathways and supports efforts to develop targeted therapies for kinase-driven diseases.