Neuropeptide K-(1-24)-peptide: storage and release by carcinoid tumors.
An antiserum directed against the COOH-terminal region of neuropeptide K-(1-24)-peptide that shows only 0.5% reactivity with neuropeptide K has been used in radioimmunoassay to study the posttranslation processing of human beta-preprotachykinin. A primary midgut carcinoid tumor contained high concentration of substance P (2970 pmol/g), neurokinin A (3660 pmol/g) and neuropeptide K-(1-24)-peptide (3430 pmol/g) but only a very low concentration (less than 5 pmol/g) of intact neuropeptide K. Neuropeptide K-(1-24)-peptide was also detected in extracts of metastatic tumor tissue from four patients with midgut carcinoid tumors. The amino acid sequence of tumor neuropeptide K-(1-24)-peptide was identical to that predicted from the nucleotide sequence of a human beta-preprotachykinin cDNA. The fasting plasma concentration of neuropeptide K-(1-24)-peptide was elevated in a patient with the carcinoid syndrome (821 fmol/ml compared with less than 18 fmol/ml in healthy subjects) and rose approximately 2-fold after intravenous pentagastrin. The study has demonstrated that the Lys25-Arg26 bond in neuropeptide K (corresponding to Lys96-Arg97 in the precursor) is an important processing site in human beta-preprotachykinin.
Conlon
J M
JM
Clinical Research Group for Gastrointestinal Endocrinology, University of Göttingen, Federal Republic of Germany.
Deacon
C F
CF
Grimelius
L
L
Cedermark
B
B
Murphy
R F
RF
Thim
L
L
Creutzfeldt
W
W
D000368:Aged; D000595:Amino Acid Sequence; D002276:Carcinoid Tumor / Q000378:metabolism*; D005260:Female; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000097:blood / Q000378:metabolism*; D010418:Pentagastrin / Q000494:pharmacology; D010446:Peptide Fragments / Q000097:blood / Q000378:metabolism*; D011863:Radioimmunoassay; D015320:Tachykinins
D009479:Neuropeptides; D010446:Peptide Fragments; D015320:Tachykinins; C045206:neuropeptide K; D010418:Pentagastrin