Cholecystokinin-associated COOH-terminal peptides are fully sulfated in pig brain.
A radioimmunoassay was developed to detect the cholecystokinin (CCK)-associated nonapeptide (CAP-9) that forms the COOH terminus of pig preproCCK. This peptide (Ser-Ala-Glu-Glu-Tyr-Glu-Tyr-Thr-Ser) is presumably produced at the time that the tyrosine-sulfated octapeptide CCK8(s) is cleaved from preproCCK. Radioimmunoassay of a dried methanol extract of pig brain revealed no detectable CAP-9 immunoreactivity, whereas acid desulfation of the dried methanol extract prior to radioimmunoassay resulted in easily measurable concentrations of CAP-9 immunoreactivity. Two peptides, CAP-9 and des-Ser9-CAP-9, were purified from a methanol extract of 8 kg of commercially obtained whole pig brains. Amino acid analysis showed that each peptide has both tyrosines sulfated. Thus, the likely sequence of CCK post-translational processing events is sulfation of the three tyrosines in the COOH terminus of preproCCK followed by peptide cleavage and appearance of CCK8(s) and CAP-9(s,s).
Eng
J
J
Gubler
U
U
Raufman
J P
JP
Chang
M
M
Hulmes
J D
JD
Pan
Y C
YC
Yalow
R S
RS
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001923:Brain Chemistry; D002766:Cholecystokinin / Q000032:analysis* / Q000276:immunology; D010446:Peptide Fragments / Q000032:analysis*; D012844:Sincalide / Q000032:analysis; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000032:analysis
D000596:Amino Acids; D010446:Peptide Fragments; C005662:tyrosine O-sulfate; D014443:Tyrosine; D002766:Cholecystokinin; D012844:Sincalide