A-1155463

Target: This ligand targets anti-apoptotic protein BCL-XL/BCL2L1 in biochemical or cellular target-engagement studies.

Mechanism of Action: Used as the target-protein recognition element, this ligand provides the binding interface for anti-apoptotic protein BCL-XL/BCL2L1. In PROTAC design, a derivatizable position on the ligand can be connected through an optimized linker to an E3 ligase ligand, such as a CRBN, VHL, or IAP recruiter, while preserving productive target engagement. The resulting bifunctional molecule brings anti-apoptotic protein BCL-XL/BCL2L1 into proximity with the recruited E3 ligase, enabling ternary-complex formation. If the complex has favorable geometry and residence time, target lysine ubiquitination is promoted, leading to proteasome-dependent degradation in experimental systems.

• PROTAC-Mediated Degradation: A-1155463 can be used as a ligand component in PROTAC designs to recruit an E3 ligase and drive selective ubiquitination of a chosen target protein. This enables systematic evaluation of degradation potency, dose–response behavior, and degradation kinetics across engineered PROTAC constructs.

• Target Engagement Optimization: Incorporating A-1155463 into PROTAC scaffolds supports structure–function studies aimed at improving target binding and ternary complex formation. Researchers can vary linker length, attachment sites, and stereochemistry to maximize productive engagement, thereby enhancing target protein turnover while minimizing off-target degradation.

• E3 Ligase Recruitment Studies: A-1155463 can serve as a defined binding moiety to probe how different E3 ligase recruiters influence ubiquitination efficiency. By pairing A-1155463 with alternative E3-binding ligands, investigators can map degradation selectivity and identify conditions that favor robust, sustained target removal.

• Mechanistic Degradation Profiling: PROTACs built with A-1155463 can be used to dissect degradation mechanisms, including dependence on the ubiquitin–proteasome system and timing of protein loss. Quantitative assays such as immunoblotting and proteomics can establish whether degradation is rapid, reversible, or influenced by cellular context.

A-1155463 is a BCL-family protein ligand intended for use as the target-engaging component or reference ligand in PROTAC discovery workflows. Its known small-molecule recognition profile enables rational linker-vector evaluation and comparative degrader design. This molecule is described in detail below.

Structure: The structure of A-1155463 is characterized by carboxylic acid or carboxylate handle; primary or secondary amine/basic nitrogen centers; halogenated aryl/heteroaryl ring system; heteroaromatic protein-recognition scaffold. These features provide defined hydrogen-bonding, hydrophobic, and steric elements that can support affinity retention while enabling analogue-based linker-vector selection.

Reactivity: The acid handle supports amide coupling with amino-PEG, alkyl-diamine, piperazine, or aminoalkyl E3-ligase ligands. For PROTAC construction, the POI ligand can be paired with CRBN ligands such as thalidomide, pomalidomide, or lenalidomide analogues, VHL ligands such as VH032 derivatives, or less common IAP/MDM2/cIAP-recruiting ligands, with alkyl, PEG, piperazine, triazole, or amide linkers screened for ternary-complex formation. In practice, incorporation into PROTACs should begin from derivatives that preserve the reported binding pharmacophore, followed by systematic variation of linker length, polarity, rigidity, and exit-vector geometry to optimize target engagement, E3 recruitment, and cellular degradation readouts.