Substance P (1-4) is the N-terminal tetrapeptide Arg-Pro-Lys-Pro-OH. It preserves the strongly basic N-terminal region of Substance P while completely removing the C-terminal sequence responsible for classical NK1 agonist recognition.

This fragment has been studied as a biologically active peptide in its own right, including hematopoietic models. Its experimental value lies in distinguishing N-terminal Substance P-derived signaling from effects mediated by the intact tachykinin pharmacophore.

Product Information

The N-Terminal Tetrapeptide Is Chemically Distinct from the NK1 Pharmacophore

SP(1-4) contains two proline residues and two strongly basic residues, Arg and Lys, but lacks the aromatic and amidated C-terminal sequence found in native Substance P.

Any biological response observed with SP(1-4) should therefore not automatically be assigned to the same mechanism as full-length Substance P.

Hematopoietic Research

SP(1-4) has been studied in erythroid progenitor models, including experiments examining endogenous erythroid colony formation and cell proliferation.

We recommend treating these effects as fragment-specific biology rather than using SP(1-4) as an NK1 reference ligand.

Research Applications

Substance P (1-4) can support N-terminal metabolite research, hematopoietic signaling studies, peptide-processing experiments and comparison of N- versus C-terminal Substance P biology.

Frequently Asked Questions

Is SP(1-4) amidated?

No. The product terminates in Pro-OH.

Does it contain the Substance P NK1 pharmacophore?

No. The C-terminal Phe-Phe-Gly-Leu-Met-NH₂ region is absent.

What is the verified CAS?

57468-16-3 for RPKP-OH.

Research Use Only.