Novel tachykinins from the brain of the sea lamprey, Petromyzon marinus, and the skate, Raja rhina.
Using radioimmunoassays for mammalian tachykinins, peptides with substance P-like immunoreactivity and neurokinin A-like immunoreactivity were identified in an extract of the brain of the longnose skate, Raja rhina (elasmobranch) but only a peptide with neurokinin A-like immunoreactivity was identified in the brain of the sea lamprey, Petromyzon marinus (agnathan). The primary structure of the skate peptide with substance P-like immunoreactivity (Ala-Lys-His-Asp-Lys-Phe-Tyr-Gly-Leu-Met-NH2) shows one amino acid substitution (Phe3-->His) compared with scyliorhinin I, previously isolated from dogfish brain and gut. The skate neurokinin A-related peptide (His-Lys-Leu-Gly-Ser-Phe-Val-Gly-Leu-Met-NH2) shows two substitutions (Thr3-->Leu and Asp4-->Gly) compared with mammalian neurokinin A. Although the COOH-terminus of the lamprey tachykinin (Arg-Lys-Pro-His-Pro-Lys-Glu-Phe-Val-Gly-Leu-Met-NH2) resembles neurokinin A, the presence of the strongly conserved Lys/Arg-Pro-Xaa-Pro motif at the NH2-terminus of the peptide indicates greater structural similarity with substance P. The additional arginine residue at position 1 in the peptide suggests that the lamprey is utilizing a site of posttranslational processing in the tachykinin precursor that is different from the equivalent site in mammalian and other lower vertebrate preprotachykinin(s).
Regulatory Peptide Center, Creighton University School of Medicine, Omaha, NE 68178.
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D
Waugh
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Sower
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Bjenning
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Conlon
D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry / Q000502:physiology*; D005260:Female; D007798:Lampreys / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D012860:Skates, Fish / Q000378:metabolism*; D013045:Species Specificity; D015320:Tachykinins / Q000302:isolation & purification*
D015320:Tachykinins