Sequence variation outside the "active" region of dog and rabbit cholecystokinin-58 results in bioactivity differences.
OBJECTIVE
We propose that regions outside the bioactive 7-amino acid carboxyl terminus of cholecystokinin (CCK)-58 influence its biological activity. Here we evaluate if sequence variation of the N-terminal regions of rabbit and canine CCK-58 changes their biological activities.


METHODS
Cholecystokinin-like immunoreactivity was purified from rabbit intestinal extracts by reverse phase and ion-exchange high-performance liquid chromatography steps. The peptide was characterized by microsequence and mass spectral characterizations of the intact and tryptic peptides. Canine and rabbit CCK-58 were evaluated for their CCK1 and CCK2 receptor binding, receptor activation, and immunologic properties.


RESULTS
The sequence of rabbit CCK-58 differs from that of canine CCK-58 in 9 of the amino terminal 40 residues. Canine CCK-58 was approximately 3-fold more potent than rabbit CCK-58 for CCK1 receptor binding and CCK2 receptor binding, but about the same potency for stimulation of amylase release from purified acinar cells. The canine peptide was 9-fold more immunoreactive than rabbit CCK-58.


CONCLUSIONS
Canine and rabbit CCK-58 have different biological and immunologic properties that can only result from differences in their N-terminal sequences which influence the properties of their identical carboxyl termini. These results are the first direct demonstration that amino acids outside the C-terminus of CCK-58 influence CCK biological activity.
Reeve
Joseph R
JR
CURE: Digestive Diseases Research Center, VA GLAHS, and Digestive Diseases Division, David Geffen School of Medicine at UCLA, Los Angeles, CA 90073, USA. jreeve@ucla.edu
Liddle
Rodger A
RA
Shively
John E
JE
Lee
Terry D
TD
Keire
David A
DA
Chew
Peter
P
Vigna
Steven R
SR
D000595:Amino Acid Sequence; D000681:Amylases / Q000378:metabolism; D000818:Animals; D002766:Cholecystokinin / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D004285:Dogs; D008969:Molecular Sequence Data; D011817:Rabbits; D043886:Receptor, Cholecystokinin A / Q000378:metabolism; D043887:Receptor, Cholecystokinin B / Q000378:metabolism; D013045:Species Specificity
D043886:Receptor, Cholecystokinin A; D043887:Receptor, Cholecystokinin B; C038823:cholecystokinin 58; D002766:Cholecystokinin; D000681:Amylases