PROTAC / TPD Building Blocks

How this supports a project

PROTAC building-block selection must define the E3-ligase system, E3-ligand exit vector, target-ligand exit vector, linker design space, assembly route, and biological test plan. A ligand-linker intermediate is not evidence of target degradation.

Treat each building block as part of a ternary system

A conventional bifunctional PROTAC combines a target-protein ligand, an E3-ligase ligand, and a linker. CRBN and VHL derivatives are common starting classes, but E3 identity, ligand stereochemistry, protected form, and exit vector must be specified for the intended assembly.

The linker affects more than distance. Composition, rigidity, polarity, branching, attachment chemistry, and both exit vectors change accessible conformations, physicochemical properties, and ternary-complex geometry. A published ligand-linker or linker length is therefore a series starting point, not a transferable degradation claim.

Typical building-block workflow

Define both ligand systems

Provide the exact target ligand and E3 ligand, their binding information, stereochemistry, functional constraints, and proposed exit vectors.

Select assembly handles

Choose protected or exposed amine, acid, alcohol, halide, azide, alkyne, or other complementary groups and define the coupling order.

Design a linker matrix

Vary length, PEG or alkyl content, rigidity, polarity, branching, and attachment orientation in a controlled series.

Choose intermediate stage

Specify E3-ligand derivative, E3 ligand-linker, target ligand-linker, complete bifunctional intermediate, or custom protected building block.

Characterize each compound

Confirm structure, identity, purity, stereochemistry, reactive-group content, residual reagents, solubility handling, and storage.

Test complete degraders

Assess target and E3 binding, ternary-complex formation, degradation, mechanism, selectivity, and function with matched controls.

Inputs for platform review

Target-ligand definition

Exact identity or structure, binding evidence, exit vector, groups to preserve, and preferred protected or activated form.

E3-ligand definition

E3 system, ligand scaffold, stereochemistry, exit vector, protected form, and literature or experimental basis.

Linker matrix

Length range, composition, rigidity, polarity, branching, terminal groups, and acceptable molecular-property range.

Synthetic stage and scale

Required intermediate type, coupling sequence, protection strategy, scale, material form, purity, and analytical methods.

Biological test plan

Assays for binding, ternary complex, degradation, proteasome and E3 dependence, selectivity, concentration and time response, and function.

Where this platform applies

This platform covers E3-ligand derivatives, ligand-linkers, PEG, alkyl or rigid linker building blocks, reactive handles, and custom bifunctional intermediates. It does not claim target binding, ternary-complex formation, degradation, cell permeability, selectivity, efficacy, safety, clinical suitability, or regulatory status.

Core considerations

CRBN and VHL ligand derivatives
PEG, alkyl, and rigid linker options
Ligand-linkers and bifunctional intermediate support

Related catalog and technical pages

PROTAC and proximity-inducing building blocksBrowse E3-ligase ligand derivatives, functionalized ligand intermediates, linkers, and related building blocks.PROTAC discoveryReview the complete workflow from both ligands and exit vectors to ternary-complex and degradation testing.Conjugation chemistry and linkersReview attachment handles, spacer design, coupling order, purification, and intermediate analysis.PEGylation and PEG linker synthesisReview discrete PEG spacer definition, terminal groups, protected intermediates, and related-species analysis.PROTAC linker selectionReview linker length, composition, flexibility, polarity, attachment points, and iteration planning.