A gonadotropin-releasing hormone type neuropeptide with a high affinity binding site for copper(ii) and nickel(ii)

Metallomics ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 404-414 ◽  
Author(s):  
Kevin K. Tran ◽  
Bhawantha M. Jayawardena ◽  
Maurice R. Elphick ◽  
Christopher E. Jones
Keyword(s):  
Binding Site ◽  
Gonadotropin Releasing Hormone ◽  
Affinity Binding ◽  
Asterias Rubens ◽  
High Affinity Binding ◽  
Releasing Hormone ◽  
High Affinity ◽  
Evolutionarily Conserved ◽  
High Affinity Site ◽  
High Affinity Binding Site

Gonadotropin releasing hormone from Asterias rubens binds Cu(ii) in a nitrogen-rich, high-affinity site. Cu(ii)-binding is an evolutionarily conserved feature of GnRH-type neuropeptides.

scholarly journals High-affinity binding site for a specific nuclear protein in the human IgM gene

Nature ◽  
1985 ◽  
Vol 315 (6016) ◽  
pp. 254-254
Author(s):  
L. Hennighausen ◽  
U. Siebenlist ◽  
D. Danner ◽  
P. Leder ◽  
D. Rawlins ◽  
...  
Keyword(s):  
Binding Site ◽  
Nuclear Protein ◽  
Affinity Binding ◽  
High Affinity Binding ◽  
High Affinity ◽  
High Affinity Binding Site ◽  
Specific Nuclear Protein

Regulatory effect of cholecystokinin on subsequent insulin binding to pancreatic acini

1990 ◽  
Vol 258 (4) ◽  
pp. E562-E568
Author(s):  
Y. Okabayashi ◽  
M. Otsuki ◽  
T. Nakamura ◽  
M. Koide ◽  
H. Hasegawa ◽  
...  
Keyword(s):  
Binding Site ◽  
Insulin Binding ◽  
Pancreatic Acinar Cells ◽  
Affinity Binding ◽  
Regulatory Effect ◽  
Pancreatic Acini ◽  
High Affinity Binding ◽  
Receptor Affinity ◽  
High Affinity ◽  
High Affinity Binding Site

We investigated the regulatory effect of cholecystokinin (CCK) on subsequent insulin binding to pancreatic acinar cells. Rat isolated acini were preincubated with various concentrations of CCK octapeptide (CCK-8) at 37 degrees C. Acini were then washed, resuspended in the binding buffer, and incubated with 8.3 pM 125I-labeled insulin for 60 min at 37 degrees C. Pretreatment with CCK-8 caused inhibition of subsequent 125I-insulin binding that was time and concentration dependent. Significant inhibition was observed with 3 pM CCK-8. Computer analysis of the competition-inhibition study with a nonlinear least-squares curve-fitting program revealed that CCK-8 pretreatment of acini reduced the receptor affinity of the high-affinity binding site. This inhibitory action of CCK-8 was not due to the alteration in degradation or internalization of the tracer. When acini were pretreated with 100 pM CCK-8 for 120 min at 4 degrees C, a reduction in the receptor affinity of the high-affinity binding site was also observed. In pancreatic membrane prepared from acini preincubated with 100 pM CCK-8 for 120 min at 37 degrees C, displacement of 125I-insulin (83 pM) by unlabeled insulin (24 degrees C, 1 h) revealed that CCK-8 inhibited 125I-insulin binding by altering the receptor affinity of the high-affinity binding site. In acinar preparations the inhibitory effect of CCK-8 on 125I-insulin binding was abolished when acini were preincubated with CCK-8 and CCK receptor antagonist L 374718 at 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Opioid receptors in bovine adrenal medulla

1984 ◽  
Vol 62 (10) ◽  
pp. 1284-1291 ◽  
Author(s):  
Michel Dumont ◽  
Simon Lemaire
Keyword(s):  
Binding Site ◽  
G Protein ◽  
Opioid Receptors ◽  
Opioid Peptides ◽  
Affinity Binding ◽  
Endogenous Opioid ◽  
High Affinity Binding ◽  
High Affinity ◽  
High Affinity Binding Site

Using prototypic ligands for each type of opioid receptors (μ, δ, κ, and σ) as well as compounds derived from each class of endogenous opioid peptides (β-endorphin, enkephalins, and dynorphins), we have undertaken the characterization of adrenomedullary opioid binding sites. The specific binding of [3H]etorphine ([3H]ET) to a membrane preparation of bovine adrenal medulla was greatly increased when the incubation temperature was raised from 22 to 37 °C. Characterization of the opioid binding sites was obtained at 37 °C with [3H]ET (nonspecific opioid ligand), [3H]ethylketocyclazocine ([3H]EKC; κ), [3H]dihydromorphine ([3H]DHM; μ), [3H]-[D-Ala2,D-Leu5]enkephalin ([3H]DADLE; δ), and N-[3H]allylnormetazocine ([3H]SKF-10047; σ) in the absence or presence of blocking agents for cross-reacting receptors. [3H]ET had a high affinity binding site (KD = 0.98 nM) with a Bmax of 119 pmol/g protein. All the other opioid compounds showed biphasic saturation curves with KD ranging from 0.6 to 1.29 nM for the high affinity binding site and from 2.49 to 12.1 nM for the low affinity binding site. The opioid μ-receptor was characterized by the high affinity binding site for [3H]DHM (KD = 1.29 nM; Bmax = 38 pmol/g protein). Blockade of the cross-reacting receptor sites for [3H]EKC, [3H]DADLE, and [3H]SKF-10047 revealed the presence of κ (KD = 0.66 nM; Bmax = 12 pmol/g protein), κ2 (benzomorphan site; KD = 11.1 nM; Bmax = 56 pmol/g protein), δ (KD = 0.67 nM; Bmax = 4.7 pmol/g protein), and σ (KD = 4.54 nM; Bmax = 32 pmol/g protein) opioid receptors. The ability of various opioid ligands to displace the binding of [3H]ET indicates a high potency for (−)-(1R,5R,9R,2″S)-5,9-dimethyl-2′-hydroxy-2-tetrahydrofurfuryl-6,7-benzomorphan hydrogen D-tartrate (MR-2034, a κ-opioid ligand; Ki = 6.2 nM), dihydromorphinone (DHMone; Ki = 6.9 nM), oxymorphone (Ki = 8.6 nM), DADLE (Ki high affinity = 8.4 nM) EKC (Ki = 31.8 nM), SKF-10047 (Ki = 75 nM), and opioid agonists/antagonists. trans-(+)-3,4-Dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide methanesulfonate hydrate (U-50,488H), the most specific κ-agonist, was a poor competitor (Ki = 5150 nM). However, the presence of κ-opioid receptors was supported by the ability of U-50,488H to displace [3H]EKC binding (Ki high affinity = 2.5 nM). The relative potency of various endogenous opioid peptides in displacing [3H]ET binding was as follows: β-endorphin [Formula: see text] dynorphin(1-17) > dynorphin(1-13) > [Arg6,Phe7)Met-enkephalin > Met-enkephalin > Leu-enkephalin. In addition, the presence of a high affinity binding site for dynorphin was demonstrated by the high potency of dynorphin (1-13) to displace [3H]EKC binding (Ki high affinity = 2.3 nM). These data provide further insights into the characterization of adrenal opioid receptors and suggest an in situ physiological role for adrenal opioid peptides.

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