Ch55-O-C3-carbaldehyde

Target: This ligand targets retinoic acid receptors RARα, RARβ, and RARγ in biochemical or cellular target-engagement studies.

Mechanism of Action: Used as the target-protein recognition element, this ligand provides the binding interface for retinoic acid receptors RARα, RARβ, and RARγ. 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 retinoic acid receptors RARα 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 E3 Ligase Recruitment: Ch55-O-C3-carbaldehyde can be used as a PROTAC ligand building block to recruit an E3 ligase through a designed linker architecture. By coupling this ligand to a target-binding moiety, researchers can create chimeric degraders that promote ubiquitination and subsequent proteasomal removal of the protein of interest.

• Targeted Proteome Degradation: The aldehyde functionality enables chemical conjugation strategies for assembling PROTACs aimed at specific protein targets. Such constructs can be optimized to tune ternary complex formation, ubiquitin transfer efficiency, and degradation potency, enabling systematic studies of how ligand geometry and linker length influence targeted proteome remodeling.

• Ternary Complex Optimization Studies: Ch55-O-C3-carbaldehyde-derived PROTACs are suitable for investigating the formation and stability of target–PROTAC–E3 ligase ternary complexes. Experimental variation of linker composition and attachment chemistry can reveal degradation determinants, including binding cooperativity and residence time, guiding rational design toward robust, selective protein knockdown.

• Mechanism-of-Degradation Validation: Incorporating this ligand into PROTAC designs supports mechanistic assays that distinguish ubiquitin-dependent degradation from non-specific inhibition. Researchers can evaluate dependence on proteasome activity, ubiquitination kinetics, and E3 ligase engagement using immunoblotting, ubiquitin conjugate detection, and rescue experiments to confirm targeted degradation pathways.

Ch55-O-C3-carbaldehyde is a retinoid receptor/CRABP 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 Ch55-O-C3-carbaldehyde is characterized by carboxylic acid or carboxylate handle; aldehyde/oxime-compatible carbonyl functionality. 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.