Direct demonstration of three different states of thepancreatic cholecystokinin receptor.

Talkad, Venugopal D.; Fortune, Kirk P.; Pollo, Dale A.; Shah, Gul N.; Wank, Stephen A.; Gardner, Jerry D.

doi:10.1073/pnas.91.5.1868

Cited by 50 publications

(27 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In a second mutant receptor, the methionine 195 was subtituted by a glutamine that is the equivalent positioned amino acid in the human CCK-B/gastrin receptor. Since the human CCK-A receptor exists in three different affinity states for sulfated CCK, we evaluated the contribution Met-195 to these different affinity states (8,9). We used the sulfated CCK-9 agonist, (Table I).…”

Section: Analysis Of the Contribution Of Methionine 195 Of The Cck-a mentioning

confidence: 99%

“…In fact, the M195L mutant demonstrated two classes of binding sites similar to the wild-type receptor. The binding parameters were modified, the high affinity sites had a (8,9). However, affinity of the low affinity sites of the M195L mutant for sulfated CCK-9 was 33-fold lower than that of the wild-type receptor (K i : 41,475 Ϯ 11,421 nM versus 1,257 Ϯ 119 nM, Table I).…”

Section: Analysis Of the Contribution Of Methionine 195 Of The Cck-a mentioning

confidence: 99%

See 1 more Smart Citation

Met-195 of the Cholecystokinin-A Receptor Interacts with the Sulfated Tyrosine of Cholecystokinin and Is Crucial for Receptor Transition to High Affinity State

Gigoux¹,

Escrieut²,

Silvente-Poirot³

et al. 1998

Journal of Biological Chemistry

View full text Add to dashboard Cite

Sulfation of the tyrosine at the seventh position from the C terminus of cholecystokinin (CCK) is crucial for CCK binding to the CCK-A receptor. Using three-dimensional modeling, we identified methionine 195 of the CCK-A receptor as a putative amino acid in interaction with the aromatic ring of the sulfated tyrosine of CCK. We analyzed the role played by the two partners of this interaction. The exchange of Met-195 for a leucine caused a minor decrease (2.8-fold) on the affinity of the high affinity sites for sulfated CCK-9, a strong drop (73%) of their number, and a 30-fold decrease on the affinity of the low and very low affinity sites for sulfated CCK-9, with no change in their number. The mutation also caused a 54-fold decrease of the potency of the receptor to induce inositol phosphates production. The high affinity sites of the wild-type CCK-A receptor were highly selective (800-fold) toward sulfated versus nonsulfated CCK, whereas low and very low affinity sites were poorly selective (10-and 18-fold). In addition, the M195L mutant bound, and responded to, sulfated CCK analogues with decreased affinities and potencies, whereas it bound and responded to nonsulfated CCK identically to the wild-type receptor. Thus, Met-195 interacts with the aromatic ring of the sulfated tyrosine to correctly position the sulfated group of CCK in the binding site of the receptor. This interaction is essential for CCK-dependent transition of the CCK-A receptor to a high affinity state. Our data should represent an important step toward the identification of the residue(s) of the receptor in interaction with the sulfate moiety of CCK and the understanding of the molecular mechanisms that govern CCK-A receptor activation. The peptide cholecystokinin (CCK)1 is found throughout the gastrointestinal system and the central nervous system where it acts both as a hormone and a neurotransmitter (1). Posttranslational processing of CCK involves sulfation of the tyrosine at position seven from the C-terminal and ␣-amidation of the C-terminal phenylalanine residue (1). Studies using chemically synthesized fragments have shown that the C-terminal sulfated and amidated octapeptide Asp-Tyr(SO 3 H)-Met-GlyTrp-Met-Asp-Phe-NH 2 (Fig. 1) exhibits the full spectrum of biological activity. However, fragments as small as the C-terminal tetrapeptide Trp-Met-Asp-Phe-NH 2 , which CCK has in common with the related peptide gastrin, retain biological activity (2).The actions of CCK are mediated by membrane receptors that are divided into two subtypes, the CCK-A and the CCK-B/gastrin (3). The cloning of the cDNA coding for these receptors has shown that they belong to the superfamily of G protein-coupled receptors which are characterized by seven transmembrane domains connected by intracellular and extracellular loops with an extracellular N-terminal and intracellular C-terminal (4, 5). Both receptor subtypes can exist in several affinity states for sulfated CCK and have in common the functional coupling to phospholipase-C, presumably via binding to a G␣...

show abstract

Section: Analysis Of the Contribution Of Methionine 195 Of The Cck-a mentioning

confidence: 99%

Section: Analysis Of the Contribution Of Methionine 195 Of The Cck-a mentioning

confidence: 99%

Met-195 of the Cholecystokinin-A Receptor Interacts with the Sulfated Tyrosine of Cholecystokinin and Is Crucial for Receptor Transition to High Affinity State

Gigoux¹,

Escrieut²,

Silvente-Poirot³

et al. 1998

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…The data in Fig. 4 Left were analyzed using the LIGAND program (20 (8)(9)(10). As illustrated in Fig.…”

mentioning

confidence: 99%

Modulation of cholecystokinin activity by albumin.

Huang¹,

Talkad²,

Fortune³

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The affinity rank order of L-364,718 and L-365,260 at the putative CCKa receptor (Ku, table 1) and at the puta tive CCKb receptor (Kji, table 1) correlated well with the corresponding affinities of these antagonists in other tissues and cells that ex press these receptor subtypes [7,27], Despite the identification of CCKA-like binding sites in mucosal homogenates, we have not been able to define further the distri bution of these putative receptors by analo gous binding experiments in enriched prepa rations of different isolated mucosal cell types (data not shown). Similarly, previous at tempts to demonstrate directly CCKA-like [125I]-BH-CCK-8s-binding sites in homoge nates from isolated guinea pig chief cells have been unsuccessful [28,29], although the ex pression of CCKa receptors by these cells is suggested by both pepsinogen secretion and cloning studies [3,30], This apparent contra diction has been explained recently by the finding that only a small fraction of the CCKA receptors on isolated guinea pig chief cells are in the high-affinity agonist-binding state [31] required for detection with [l25I]-BH-CCK-8s [32]. Since we and others did not encounter this problem in binding studies with homoge nates from intact porcine gastric mucosa or from dispersed guinea pig gastric glands (see above), it is possible that a transition towards lower agonist affinity is induced by the pro cess of chief cell isolation.…”

Section: Discussionmentioning

confidence: 99%

Characterization of CCK<sub>A</sub> Receptor Mediated Pepsinogen Secretion in Porcine Chief Cells

Meyer

Beinborn²,

Sewing³

1996

Pharmacology

View full text Add to dashboard Cite

Cholecystokinin octapeptide (CCK-8s) is an endogenous stimulus of gastric pepsinogen secretion. Previous studies with isolated guinea pig chief cells indicated that this process is mediated through the CCK_A receptor subtype, with an additional contribution from CCK_B receptors. For comparison, we examined the mechanism of CCK-8s stimulated pepsinogen secretion in a larger nonrodent species, using highly enriched porcine chief cells as a functional in vitro model. Porcine chief cells responded weakly to stimulation by CCK-8s alone, but the efficacy was markedly enhanced in the presence of 10 µmol l^–1 forskolin. Under these conditions, pepsinogen secretion was potently stimulated by CCK-8s and the CCKa receptor selective heptapeptide, A-71,378 (EC50 = 4.7 and 33 nmol H), but not by CCK_B receptor selective agonists. The prototype CCKa receptor selective antagonist L-364,718 blocked pepsinogen secretion with ∼2,000-fold higher affinity than the CCK_B receptor selective analogue, L-365,260. This functional profile was consistent with the affinity rank order of all tested compounds at CCK_A-receptor-like [¹²⁵I]-BH-CCK-8s binding sites in the porcine gastric mucosa. Comparison with cloned CCK_A receptors from other species revealed that the receptors mediating pepsinogen secretion in the pig have similar pharmacology, possibly with slight differences in agonist potencies. In contrast to the guinea pig, porcine CCK_B receptors appear to have no direct role in pepsinogen secretion.

show abstract

Direct demonstration of three different states of thepancreatic cholecystokinin receptor.

Cited by 50 publications

References 31 publications

Met-195 of the Cholecystokinin-A Receptor Interacts with the Sulfated Tyrosine of Cholecystokinin and Is Crucial for Receptor Transition to High Affinity State

Met-195 of the Cholecystokinin-A Receptor Interacts with the Sulfated Tyrosine of Cholecystokinin and Is Crucial for Receptor Transition to High Affinity State

Modulation of cholecystokinin activity by albumin.

Characterization of CCK<sub>A</sub> Receptor Mediated Pepsinogen Secretion in Porcine Chief Cells

Contact Info

Product

Resources

About