Programmed cell death 1 ligand 1 (15-23)

Programmed cell death 1 ligand 1 (15-23) is a synthetic peptide fragment derived from the PD-L1 protein, specifically encompassing amino acid residues 15 through 23. As a segment of the immune checkpoint ligand PD-L1, this peptide is of significant interest in immunological and biochemical research due to its involvement in modulating T-cell activity via the PD-1/PD-L1 pathway. Its defined sequence enables researchers to study discrete interaction domains, structure-function relationships, and molecular recognition events that underpin immune evasion mechanisms and cellular signaling processes. The availability of this peptide fragment facilitates targeted investigations into the functional motifs of PD-L1 and their broader implications in immune regulation.

Epitope mapping: The 15-23 fragment of PD-L1 serves as a valuable reagent for epitope mapping studies aimed at identifying antibody or T-cell receptor binding sites. By incorporating this peptide into binding assays, researchers can dissect the specific residues responsible for interaction with immune components, thereby elucidating the antigenic determinants critical for immune recognition. Such insights are essential for the rational design of monoclonal antibodies or engineered T-cell receptors with enhanced specificity for PD-L1, advancing the development of novel immunotherapeutic strategies.

Protein-protein interaction analysis: Utilization of the PD-L1 (15-23) peptide in protein-protein interaction studies allows for detailed assessment of the PD-1/PD-L1 interface at the molecular level. Through techniques such as surface plasmon resonance, isothermal titration calorimetry, or peptide pull-down assays, the fragment can be employed to investigate binding affinities, kinetic parameters, and structural determinants governing checkpoint signaling. These analyses contribute to a deeper understanding of how discrete peptide motifs influence the formation and stability of immune checkpoint complexes.

Peptide-based inhibitor screening: The defined sequence of this PD-L1 peptide fragment makes it an ideal substrate for high-throughput screening of small molecules or peptides designed to disrupt the PD-1/PD-L1 interaction. By incorporating the 15-23 region into competitive binding assays, researchers can rapidly assess the efficacy of candidate inhibitors in blocking the critical contact points between PD-1 and its ligand. This approach accelerates the identification and optimization of lead compounds for further development in immunomodulatory research.

Structural biology: The PD-L1 (15-23) peptide is frequently used as a model system in structural biology investigations, including nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography. Its well-defined sequence and manageable size facilitate high-resolution analysis of peptide conformations, backbone dynamics, and side-chain interactions, both in isolation and in complex with binding partners. Structural insights gained from such studies are instrumental in elucidating the molecular underpinnings of immune checkpoint regulation and informing rational peptide engineering efforts.

Immunoassay development: Incorporating the PD-L1 (15-23) fragment into immunoassays, such as enzyme-linked immunosorbent assays (ELISA) or multiplex bead-based platforms, enables the sensitive and specific detection of PD-L1-reactive antibodies or T cells in biological samples. The use of this peptide as a capture antigen or probe supports the quantitative measurement of immune responses, biomarker validation, and the monitoring of immune checkpoint modulation in experimental systems. Such assays are indispensable tools for translational research and the evaluation of immunotherapeutic interventions in preclinical settings.

1. Proinsulin C-peptide and insulin: Limited pattern similarities of interest in inter-peptide interactions but no C-peptide effect on insulin and IGF-1 receptor signaling

2. Application of human liver organoids as a patient-derived primary model for HBV infection and related hepatocellular carcinoma

3. Cationic cell-penetrating peptides are potent furin inhibitors

4. Odorant binding protein based biomimetic sensors for detection of alcohols associated with Salmonella contamination in packaged beef

5. Adipose tissue is a key organ for the beneficial effects of GLP-2 metabolic function