Substance-P-related and neurokinin-A-related peptides from the brain of the cod and trout.
An extract of the brain of the rainbow trout, Oncorhynchus mykiss contained high concentrations of both neurokinin A-like immunoreactivity (corresponding to 90 pmol mammalian neurokinin A/g wet tissue) and substance-P-like immunoreactivity (corresponding to 50 pmol mammalian substance P/g wet tissue) measured by radioimmunoassay using antisera directed against the C-terminal regions of the mammalian peptides. In contrast, an extract of the Atlantic cod. Gadus morhua contained only neurokinin-A-like immunoreactivity (151 pmol/g). This apparent paradox was resolved by determination of the primary structures of the fish tachykinins. Trout substance P (Lys-Pro-Arg-Pro-His-Gln-Phe-Phe-Gly-Leu-MetNH2) has the same amino acid sequence in its C-terminal region as that in the corresponding region of mammalian substance P. Cod substance P (Lys-Pro-Arg-Pro-Gln-Gln-Phe-Ile-Gly-Leu-MetNH2), however, contains a substitution at position 8 (Phe----Ile) that abolishes reactivity with the antiserum to substance P but permits reactivity with the antiserum to neurokinin A. The amino acid sequence of cod and trout neurokinin A is the same (His-Lys-Ile-Asn-Ser-Phe-Val-Gly-Leu-MetNH2) and shows two substitutions (Thr3----Ile and Asp4----Asn) compared with mammalian neurokinin A. The data indicate that nervous tissue of teleost fish contain tachykinins that are analogous to the peptides found in mammalian tissues.
Jensen
J
J
Department of Biomedical Sciences, Creighton University, School of Medicine, Omaha, NE 68178.
Conlon
J M
JM
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001923:Brain Chemistry; D005399:Fishes; D008969:Molecular Sequence Data; D015288:Neurokinin A / Q000032:analysis* / Q000737:chemistry; D011863:Radioimmunoassay; D013373:Substance P / Q000032:analysis* / Q000737:chemistry; D014337:Trout
D000596:Amino Acids; D013373:Substance P; D015288:Neurokinin A