Independent research interface · Four open source layers · Not clinical guidance

Read the provenance
Cell-Penetrating PeptidesResearch atlas

2026 multi-source atlas

How peptides cross the line

Move from sequence to evidence across CPPsite3, quantitative POSEIDON experiments, and positive CellPPD benchmark collections—without losing the source, cargo, model, modification, or uptake context.

Explore the database Understand the evidence

Scientific facts are attributed to their named source. Dataset membership supports discovery; it is not a universal claim of safety, efficacy, or mechanism. This positive-only atlas is not a classifier training set without independently sourced negatives. CPPsite3 reports literature coverage through April 2024.

Membrane encounterContext-dependent
Peptide and membrane interaction A schematic peptide chain approaches a phospholipid bilayer and continues into the cell. This is an explanatory diagram, not a single established mechanism. EXTRACELLULAR CYTOSOL
GRKKRRQRRRPPQ
7,271searchable source records
4,763distinct sequence strings
1,859unique linked PubMed identifiers
483supplemental sequence records

A layered evidence map

One search. Four distinct source roles.

CPPsite3 supplies 6,788 of 7,271 records; the other collections add quantitative and positive-benchmark layers. Every result keeps an atlas precedence dataset and evidence class. Cross-source listings can reflect shared upstream literature or curation and are not independent confirmation.

See the merge and deduplication method
4,763sequence strings
CPPsite36,788 curated records
POSEIDON350 quantitative records
CellPPD100 positive benchmarks
CellPPD-Mod33 modified positives

A better research question

Not “does it penetrate?”—but when, where, and with what?

CPP uptake can shift with peptide concentration, cargo, cell line, and experimental conditions. This interface keeps those qualifiers beside the sequence rather than flattening them into a single claim.

Find the sequence

Search by peptide name, identifier, PubMed ID, or an amino-acid segment. Exact and partial sequence matching are both available.

Keep the experiment attached

Review cargo, cell line, in vitro or in vivo context, uptake description, and reported modifications before comparing records.

Return to the paper

Use the PubMed link as the evidence boundary. Database fields help discovery; the primary experiment supports interpretation.

Editorial explainer

Entry is a route, not a verdict

Two broad routes dominate CPP discussions: endocytic uptake and direct plasma-membrane translocation. The relative contribution can depend on the peptide, cargo, concentration, membrane, and assay. Endocytic entry also raises a second problem: escape from intracellular vesicles.

Explore uptake mechanisms

Simplified routes for cell-penetrating peptide uptake A cell membrane branches into an endocytic vesicle route and a direct translocation route, with both leading toward the cytosol. OUTSIDE CELL ENDOCYTIC ROUTE DIRECT ROUTE CYTOSOLIC ACCESS
Endocytic entryMembrane-bound uptake; productive delivery may require endosomal escape.
Direct translocationEnergy-independent routes are reported, but the molecular mechanism is still actively studied.

Source-backed evidence note

“Experimentally validated” does not mean universally transferable.

Editorial guidance: interpret each CPP record within its reported assay, cargo, concentration, cell system, and publication.

Search the research layer

Start with a name, PMID, or sequence segment

Try Tat, HeLa, nucleic acid, or an amino-acid motif such as RRQRRR.