Secretin receptors in a new preparation of plasma membranes from intrahepatic biliary epithelium.
Secretin is thought to cause choleresis by acting on a receptor expressed by bile duct epithelial cells. In this study, the receptor was characterized using a new preparation of intrahepatic bile duct plasma membranes. Hyperplastic biliary trees were obtained from 3-week bile duct-ligated rats. The biliary trees were homogenized, filtered, and subjected to an aqueous two-phase partition technique to yield highly purified plasma membranes (confirmed by a 14-fold enrichment in gamma-glutamyl transpeptidase activity and a 10-fold enrichment in 125I-secretin binding). 125I-secretin bound saturably with high affinity and in a dose-dependent fashion (Kd = 1.3 +/- 0.1 nM, Bmax = 273 +/- 23 fmole/mg) to purified plasma membranes. The binding characteristics of secretin were most consistent with a single site receptor model. Competitive binding studies indicated that the secretin-related peptides glucagon, peptide histidine isoleucine, gastric inhibitory peptide, and growth hormone releasing factor did not inhibit binding. Vasoactive intestinal peptide (1 microM) reduced maximal binding by 19 +/- 1%. The GTP analogs guanylylimidodiphosphate and guanosine 5'-O-[3-thiotriphosphate] (1 microM) inhibited binding by 16 +/- 2 and 13 +/- 1%, respectively. In conclusion, secretin binds to a specific, high-affinity receptor in intrahepatic bile duct epithelium that is coupled to a G-protein-linked signal transduction system.
Farouk
M
M
Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710.
Vigna
S R
SR
Haebig
J E
JE
Gettys
T W
TW
McVey
D C
DC
Chari
R
R
Pruthi
R S
RS
Meyers
W C
WC
D000818:Animals; D001653:Bile Ducts, Intrahepatic / Q000378:metabolism*; D001667:Binding, Competitive; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism*; D012633:Secretin / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; C029937:secretin receptor; D012633:Secretin; D006165:Guanylyl Imidodiphosphate; D014660:Vasoactive Intestinal Peptide; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D005723:gamma-Glutamyltransferase