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).
Waugh
D
D
Regulatory Peptide Center, Creighton University School of Medicine, Omaha, NE 68178.
Sower
S
S
Bjenning
C
C
Conlon
J M
JM
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