SV40 NLS is a short, lysine-rich nuclear localization signal derived from the large T antigen of Simian Virus 40. The classical minimal recognition motif PKKKRKV is one of the best-characterized monopartite nuclear localization signals and is widely used as a reference sequence for studying importin-dependent nuclear transport.
AS2736 contains the sequence PKKKRKVG, incorporating the canonical seven-residue SV40 NLS motif followed by a C-terminal glycine. Its compact size and strongly basic character make it useful in studies of nuclear targeting, protein localization, importin recognition, and NLS-dependent cargo transport.
Product Information
| Property | Specification |
|---|---|
| Product Name | SV40 NLS |
| Catalog No. | AS2736 |
| Sequence | PKKKRKVG |
| Length | 8 amino acids |
| SV40 NLS Core | PKKKRKV |
| Molecular Formula | C₄₂H₈₁N₁₅O₉ |
| Molecular Weight | 940.21 Da |
| CAS No. | 95088-49-6 |
| Signal Type | Classical monopartite NLS |
| Primary Research Area | Nuclear import and intracellular localization |
| Purity | Crude to 98% |
| Form | Lyophilized peptide |
SV40 NLS belongs to Alan Scientific's Nuclear Localization Signals (NLS) collection of peptide signals used to investigate intracellular trafficking and nuclear transport.
Classical SV40 NLS and Importin Recognition
Classical nuclear localization signals are typically enriched in lysine and arginine residues. The SV40 large T-antigen sequence PKKKRKV is the prototype monopartite NLS and is recognized primarily through the NLS-binding region of importin-α.
Importin-α functions as an adaptor in the classical nuclear import pathway. Following cargo recognition, importin-β participates in transport of the complex through the nuclear pore system, while Ran-dependent events in the nucleus contribute to cargo release.
The SV40 sequence has therefore become a common experimental reference for investigating how basic peptide motifs control nuclear accumulation.
Why the Basic Residues Matter
The clustered Lys and Arg residues are not simply a general positive-charge tag. Their position within the NLS contributes to recognition by importin-α.
Changes within the core motif can alter receptor affinity and nuclear localization efficiency, making SV40 NLS useful for sequence-mutagenesis experiments, comparison of NLS strength, and studies of nuclear transport specificity.
Research Applications
AS2736 can be used in nuclear import studies, NLS–importin interaction research, intracellular localization experiments, fusion-protein design, and comparative studies of nuclear targeting sequences.
The peptide is also useful as a compact reference sequence when evaluating engineered NLS variants. Researchers can compare substitutions, tandem NLS motifs, altered spacers, or different terminal extensions while retaining the well-characterized SV40 sequence as a baseline.
For projects requiring NLS sequence variants, fluorescent labeling, terminal modification, conjugation handles, or incorporation into longer peptides, our Custom Peptide Synthesis capabilities can support project-specific designs.
NLS Function Depends on Cargo Context
An NLS does not function independently of every experimental variable. Nuclear accumulation can be influenced by cargo size, accessibility of the signal, copy number, linker design, orientation, importin expression, and the cellular system being studied.
Flanking sequences can also affect how effectively an NLS is recognized. For this reason, activity observed with a free peptide should not automatically be assumed to match the behavior of the same motif when embedded within a protein or conjugated to another macromolecule.
For researchers requiring a sequence specifically designed for chemical attachment to cargo, SV40 Nuclear Transport Signal Peptide Analog (AS2737) provides an extended 13-residue format containing an N-terminal cysteine.
Quality and Laboratory Planning
For short, highly basic peptides such as SV40 NLS, molecular identity and chromatographic purity should be considered together with the intended downstream application.
Analytical HPLC can assess chromatographic purity, while mass spectrometry supports confirmation of molecular identity. For experiments involving conjugation, fluorescence labeling, or quantitative comparison between NLS variants, consistent peptide specification and lot documentation can improve experimental reproducibility.
Additional analytical information is available through our Peptide Quality Control resource.
Storage and Handling
Store lyophilized SV40 NLS according to the conditions specified for the supplied batch and protect the material from moisture.
After reconstitution, solvent composition, concentration, temperature, and storage duration should be kept consistent across comparative nuclear-localization experiments.
Research Use Only
SV40 NLS is supplied for research use only. It is not intended for therapeutic, or human use.