Description_x000D_ Amino Acid Sequence_x000D_ Arg-Pro-Lys-Pro-Gln-Gln-Phe-Tyr-Gly-Leu-Met-NH2_x000D_ Application_x000D_ Substance P is a tachykinin family 11 amino acid neuropeptide involved in neurotransmission and neuromodulation. Substance P acts via the neurokinin-1 receptor (NK1-receptor, NK1R). [Tyr8]-Substance P is used as a biologically active analogue of Substance P. [Tyr8] SP is often used as a radioligand tracer in studies of Substance P binding and distribution.