Isolation and structural determination of rat neuromedin U

Rat neuromedin U was isolated from the small intestine using mainly immunoaffinity chromatography and radioimmunoassay for pig neuromedin U-8. The amino acid sequence of rat neuromedin U was determined by microsequence analysis to be Tyr-Lys-Val-Asn-Glu-Tyr-Gln-Gly-Pro-Val-Ala-Pro-Ser-Gly-Gly- Phe-Phe-Leu-Phe-Arg-Pro-Arg-Asn-NH2, and this structure was confirmed by synthesis. Although the C-terminal heptapeptide amide structure of pig neuromedin U is completely conserved in rat neuromedin U, the remainder of the peptide reveals nine amino acid replacements and two amino acid deletions when compared to pig neuromedin U-25. Rat neuromedin U exerts two-fold potent uterus stimulant activity as compared to pig neuromedin U-25.