Identification of a VIP-specific receptor in guinea pig tenia coli.
Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) interact with VPAC(2) receptors in rabbit and guinea pig (GP) gastric muscle but with functionally distinct VIP and PACAP receptors in GP tenia coli. This study examined whether selectivity for VIP was determined by two residues (40, 41) in the extracellular domain that differ in the VIP receptors of GP gastric and tenial muscle. A mutant rat VPAC(2) receptor (L40F, L41F), and two chimeric receptors in which the NH(2)-terminal domain of rat VPAC(2) receptor was replaced with that of GP gastric (chimeric-G) or tenia coli (chimeric-T) VIP receptors, were constructed and expressed in COS-1 cells. VIP and PACAP bound with equal affinity to wild-type and mutant rat VPAC(2) receptors and to chimeric-G receptor (IC(50): VIP 0.3 +/- 0.1 to 1.5 +/- 0.4 nM, PACAP 0.4 +/- 0.1 to 2.5 +/- 0.1 nM) and stimulated cAMP with equal potency (EC(50): VIP 13 +/- 5 to 48 +/- 8 nM, PACAP 8 +/- 3 to 31 +/- 14 nM). VIP bound with high affinity also to chimeric-T receptor (IC(50): 0.5 +/- 0.1 nM) and stimulated cAMP with high potency (EC(50): 3 +/- 1 nM). In contrast, PACAP exhibited >1,000-fold less affinity for binding or potency for stimulating cAMP. We conclude that GP tenia coli express a VIP-specific receptor and that selectivity is determined by a pair of extracellular phenylalanine residues.
Teng
B Q
BQ
Departments of Physiology and Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298-0711, USA.
Grider
J R
JR
Murthy
K S
KS
D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D019556:COS Cells; D003106:Colon / Q000378:metabolism*; D000242:Cyclic AMP / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression; D006168:Guinea Pigs; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009479:Neuropeptides / Q000378:metabolism / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D017434:Protein Structure, Tertiary / Q000235:genetics; D051381:Rats; D018005:Receptors, Vasoactive Intestinal Peptide / Q000235:genetics / Q000378:metabolism*; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013379:Substrate Specificity / Q000235:genetics; D014162:Transfection; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism* / Q000494:pharmacology
C495403:Adcyap1 protein, rat; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018005:Receptors, Vasoactive Intestinal Peptide; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D011993:Recombinant Fusion Proteins; D014660:Vasoactive Intestinal Peptide; D000242:Cyclic AMP; D000262:Adenylyl Cyclases