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1hzn

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NMR SOLUTION STRUCTURE OF THE THIRD EXTRACELLULAR LOOP OF THE CHOLECYSTOKININ A RECEPTOR

Structural highlights

1hzn is a 1 chain structure with sequence from Homo sapiens. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Solution NMR, 1 model
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

CCKAR_HUMAN Receptor for cholecystokinin. Mediates pancreatic growth and enzyme secretion, smooth muscle contraction of the gall bladder and stomach. Has a 1000-fold higher affinity for CCK rather than for gastrin. It modulates feeding and dopamine-induced behavior in the central and peripheral nervous system. This receptor mediates its action by association with G proteins that activate a phosphatidylinositol-calcium second messenger system.

Publication Abstract from PubMed

The interaction of the C-terminal octapeptide of cholecystokinin, CCK-8, with the third extracellular loop of human cholecystokinin-A receptor, CCK(A)-R(329-357), has been probed by high-resolution NMR and extensive computer simulations. The structure of CCK(A)-R(329-357) in the presence of dodecylphosphocholine micelles consists of three alpha-helices, with the first and third corresponding to the extracellular ends of transmembrane (TM) helices 6 and 7. The central helix, residues W335-R345, is found to lie on the zwitterionic surface. Titration with CCK-8 produces a stable complex with a number of intermolecular NOEs between the C-terminus of the ligand (Trp(30), Met(31), Asp(32)) and the interface of TM6 and the third extracellular loop (N333, A334, Y338) of the receptor fragment. The mode of ligand binding based on these intermolecular NOEs is in agreement with a number of published findings from receptor mutagenesis and photoaffinity cross-linking. Utilizing these ligand/receptor points of interaction, the structural features of CCK(A)-R(329-357), and also the structures of CCK-8 and CCK(A)-R(1-47) previously determined, extensive molecular dynamics simulations of the CCK-8/CCK(A)-R complex were carried out. The results provide unique insight into the molecular interactions and forces important for the binding of CCK-8 to CCK(A)-R.

Intermolecular interactions between cholecystokinin-8 and the third extracellular loop of the cholecystokinin A receptor.,Giragossian C, Mierke DF Biochemistry. 2001 Apr 3;40(13):3804-9. PMID:11300760^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Giragossian C, Mierke DF. Intermolecular interactions between cholecystokinin-8 and the third extracellular loop of the cholecystokinin A receptor. Biochemistry. 2001 Apr 3;40(13):3804-9. PMID:11300760