scholarly journals Binding of insulin to solubilized insulin receptor from human placenta. Evidence for a single class of noninteracting binding sites.

1983 ◽  
Vol 258 (12) ◽  
pp. 7460-7468 ◽  
Author(s):  
R A Kohanski ◽  
M D Lane
Keyword(s):  
Insulin Receptor ◽  
Human Placenta ◽  
Binding Sites ◽  
Single Class

Characterization and ontogeny of endothelin receptors in human placenta

1993 ◽  
Vol 264 (3) ◽  
pp. E367-E372 ◽  
Author(s):  
S. J. Kilpatrick ◽  
J. M. Roberts ◽  
D. L. Lykins ◽  
R. N. Taylor
Keyword(s):  
Human Placenta ◽  
Binding Sites ◽  
Pregnancy Termination ◽  
First Trimester ◽  
Receptor Subtype ◽  
Rt Pcr ◽  
Third Trimester ◽  
Single Class ◽  
Mrna Transcripts ◽  
Polymerase Chain

Because of the potent mitogenic and vasoactive properties of endothelin-1 (ET-1) and the presence of its receptor in third trimester placenta, we postulated that ET-1 might be involved in human placental growth and vascularization during development. As an initial approach to test this hypothesis, placental ET receptors were characterized and quantified in each trimester of pregnancy. Membrane-rich particulates were prepared from first-, second-, and third-trimester villous human placenta obtained immediately after pregnancy termination or delivery. ET receptors were characterized by radioligand saturation analysis, ligand competition, and reverse transcription-polymerase chain reaction (RT-PCR) to determine the concentration, affinity, and specificity of ET binding sites, and to document the presence of specific ET-receptor subtype mRNA transcripts in placentas from each trimester. Kinetic determinations of 125I-labeled ET-1 binding yielded a Kd = 61 pM, consistent with the equilibrium determinations of 34 +/- 6 pM (n = 11). The concentration of ET receptors decreased significantly from 682 +/- 94 fmol/mg protein (n = 4) in the first trimester to 266 +/- 89 fmol/mg protein (n = 4) in the third trimester. Competition studies with unlabeled ET-1 indicated a single class of binding sites with a Ki = 49 +/- 5 pM (n = 9), whereas competition with ET-3 demonstrated binding sites with two affinities. The predominant sites had a Ki = 84 +/- 14 pM, similar to that for ET-1. The RT-PCR data confirmed that both ETA and ETB receptors mRNA transcripts are expressed in human placenta.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of Thromboxane A2/Prostaglandin H2 Receptors in Porcine Coronary Artery -The Inhibitory Effect of a Novel Dibenzoxepin Derivative, KW-3635

1992 ◽  
Vol 67 (05) ◽  
pp. 582-584 ◽  
Author(s):  
Ichiro Miki ◽  
Akio Ishii
Keyword(s):  
Coronary Artery ◽  
Binding Sites ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Scatchard Analysis ◽  
Single Class ◽  
Porcine Coronary Artery ◽  
Equilibrium Binding ◽  
H2 Receptors

SummaryWe characterized the thromboxane A2/prostaglandin H2 receptors in porcine coronary artery. The binding of [3H]SQ 29,548, a thromboxane A2 antagonist, to coronary arterial membranes was saturable and displaceable. Scatchard analysis of equilibrium binding showed a single class of high affinity binding sites with a dissociation constant of 18.5 ±1.0 nM and the maximum binding of 80.7 ± 5.2 fmol/mg protein. [3H]SQ 29,548 binding was concentration-dependently inhibited by thromboxane A2 antagonists such as SQ 29,548, BM13505 and BM13177 or the thromboxane A2 agonists such as U46619 and U44069. KW-3635, a novel dibenzoxepin derivative, concentration-dependently inhibited the [3H]SQ 29,548 binding to thromboxane A2/prosta-glandin H2 receptors in coronary artery with an inhibition constant of 6.0 ± 0.69 nM (mean ± S.E.M.).

scholarly journals Localization of the insulin receptor binding sites for the SH2 domain proteins p85, Syp, and GAP.

1994 ◽  
Vol 269 (44) ◽  
pp. 27186-27192
Author(s):  
P A Staubs ◽  
D R Reichart ◽  
A R Saltiel ◽  
K L Milarski ◽  
H Maegawa ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Receptor Binding ◽  
Binding Sites ◽  
Sh2 Domain ◽  
Insulin Receptor Binding

Regulation of ANG II and AVP receptors in isolated hepatocytes of pregnant rats

1990 ◽  
Vol 258 (4) ◽  
pp. E597-E605
Author(s):  
G. Massicotte ◽  
L. Coderre ◽  
J. L. Chiasson ◽  
G. Thibault ◽  
E. L. Schiffrin ◽  
...  
Keyword(s):  
Binding Sites ◽  
Rat Hepatocytes ◽  
Isolated Hepatocytes ◽  
Maximum Response ◽  
Receptor Subtype ◽  
Ang Ii ◽  
Single Class ◽  
Pregnant Rats ◽  
Isolated Rat Hepatocytes ◽  
Biological Responses

Recent evidence suggests that angiotensin II (ANG II) and vasopressin (AVP) act on the liver via specific receptors. We have examined the binding properties of these receptors in isolated rat hepatocytes and studied the regulation of the biological responses to ANG II and AVP during pregnancy in the rat. In contrast to [3H]ANG II, 125I-labeled-[Sar1-Ile8]ANG II was markedly resistant to degradation by isolated liver cells. Displacement and saturation experiments with this iodinated antagonist revealed the presence of a single class of binding sites [2 x 10(5) sites/cell, dissociation constant (KD) = 1.0 nM]. The potency of ANG II analogues to displace 125I-[Sar1-Ile8]-ANG II agrees closely with data reported for vascular smooth muscle cells. Isolated hepatocytes have approximately 8 x 10(4) [3H]AVP binding sites/cell (KD = 1.0 nM) based on saturation experiments. AVP analogues selectively displaced [3H]AVP, suggesting the presence of V1-AVP receptor subtype. The maximum response of [Sar1]ANG II-induced glycogenolysis in the cells was decreased during gestation, whereas the effective concentration producing 50% of maximum response (EC50) was significantly increased (0.15-0.28 nM) when compared with cells from nonpregnant animals. In pregnancy, receptors for 125I-[Sar1-Ile8]ANG II were not changed in affinity (KD) or in density (Bmax). The maximum response and EC50 of AVP on liver glycogenolysis were not significantly decreased during pregnancy, whereas an increased number of AVP binding sites (from 5.0 +/- 0.5 x 10(4) to 11.0 +/- 1.7 x 10(4)) with similar KD was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Ontogeny of imidazoline binding sites in the human placenta

1999 ◽  
Vol 78 (2) ◽  
pp. 89-92 ◽  
Author(s):  
Krisztina Bagaméry ◽  
László Kovács ◽  
Sándor Viski ◽  
Tibor Nyári ◽  
György Falkay
Keyword(s):  
Human Placenta ◽  
Binding Sites ◽  
Imidazoline Binding Sites

scholarly journals Differential localization of endothelin ETa and ETB binding sites in human placenta

1993 ◽  
Vol 109 (2) ◽  
pp. 544-552 ◽  
Author(s):  
Richard A.D. Rutherford ◽  
John Wharton ◽  
Andrew McCarthy ◽  
Lee Gordon ◽  
Mark H.F. Sullivan ◽  
...  
Keyword(s):  
Human Placenta ◽  
Binding Sites ◽  
Differential Localization

scholarly journals Cryo-EM structure of the complete and ligand-saturated insulin receptor ectodomain

2019 ◽  
Author(s):  
Theresia Gutmann ◽  
Ingmar Schäfer ◽  
Chetan Poojari ◽  
Beate Brankatschk ◽  
Ilpo Vattulainen ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Binding Sites ◽  
Structural Model ◽  
Receptor Site ◽  
Insulin Binding ◽  
Proximal Region ◽  
Dynamics Simulation ◽  
Structural Basis ◽  
Structure Based Drug Design ◽  
Receptor Interactions

AbstractGlucose homeostasis and growth essentially depend on the peptide hormone insulin engaging its receptor. Despite biochemical and structural advances, a fundamental contradiction has persisted in the current understanding of insulin ligand–receptor interactions. While biochemistry predicts two distinct insulin binding sites, 1 and 2, recent structural analyses have only resolved site 1. Using a combined approach of cryo-EM and atomistic molecular dynamics simulation, we determined the structure of the entire dimeric insulin receptor ectodomain saturated with four insulin molecules. Complementing the previously described insulin–site 1 interaction, we present the first view of insulin bound to the discrete insulin receptor site 2. Insulin binding stabilizes the receptor ectodomain in a T-shaped conformation wherein the membrane-proximal domains converge and contact each other. These findings expand the current models of insulin binding to its receptor and of its regulation. In summary, we provide the structural basis enabling a comprehensive description of ligand–receptor interactions that ultimately will inform new approaches to structure-based drug design.In briefA cryo-EM structure of the complete insulin receptor ectodomain saturated with four insulin ligands is reported. The structural model of the insulin–insulin receptor complex adopts a T-shaped conformation, reveals two additional insulin-binding sites potentially involved in the initial interaction of insulin with its receptor, and resolves the membrane proximal region.

Identification and characterization of a corticotrophin-releasing hormone receptor in human placenta

1995 ◽  
Vol 133 (5) ◽  
pp. 591-597 ◽  
Author(s):  
Vicki L Clifton ◽  
Phillip C Owens ◽  
Phillip J Robinson ◽  
Roger Smith
Keyword(s):  
Human Placenta ◽  
Binding Sites ◽  
Hormone Receptor ◽  
Human Myometrium ◽  
Scatchard Analysis ◽  
Releasing Hormone ◽  
Rat Pituitary ◽  
Identification And Characterization ◽  
Crh Receptors

Clifton VL, Owens PC, Robinson PJ, Smith R. Identification and characterization of a corticotrophinreleasing hormone receptor in human placenta. Eur J Endocrinol 1995;133:591–7. ISSN 0804–4643 Corticotrophin-releasing hormone (CRH) causes vasodilatation in the human fetal–placental circulation and has paracrine actions in placental tissue, suggesting that CRH receptors may be present in the human placenta. We have now identified and characterized placental CRH binding sites and compared them to those described previously in human myometrium and rat pituitary. Radiolabelled ovine CRH binding to placental membranes was pH-, time-, temperature- and divalent cation-dependent and was reversible in the presence of 1 μmol/l unlabelled ovine CRH. Scatchard analysis of placentae delivered vaginally or by elective caesarean section revealed dissociation constants (Kd) of 214.5 ± 84 pmol/l (N = 8) and 45.4 ± 23.9 pmol/l (N = 9), respectively. The Kd for caesarean placental binding sites was similar to that of human myometrium (59.6 pmol/l, N = 3) and rat pituitary (82.5 pmol/l, N = 3) receptors. However, in vaginally delivered placentae the CRH binding sites had a much lower affinity (p < 0.05). The receptor densities (Bmax) of vaginally delivered and caesarean-delivered placentae were 28.6 ± 9.6 and 6.1 ± 2.8 fmol/mg, respectively (p < 0.05). Chemical cross-linking studies using disuccinimidyl suberate indicated that the molecular weight of the CRH receptor in the placenta and rat pituitary is 75 kD. We conclude that there is a high-affinity population of CRH binding sites in the human placenta that are physicochemically similar to pituitary and myometrial CRH receptors. The CRH receptor properties in the placenta change in response to labour, when CRH levels in maternal blood are highest, suggesting that placental CRH may regulate its receptor. R Smith, Endocrinology Unit, John Hunter Hospital, Locked Bag 1, Hunter Regional Mail Centre, Newcastle, NSW 2310, Australia

Corticosterone's metabolite is an agonist for Na+ transport stimulation in A6 cells

1988 ◽  
Vol 255 (4) ◽  
pp. F736-F748 ◽  
Author(s):  
R. L. Duncan ◽  
W. M. Grogan ◽  
L. B. Kramer ◽  
C. O. Watlington
Keyword(s):  
Binding Sites ◽  
Short Circuit ◽  
Type I ◽  
Type Ii ◽  
Na Transport ◽  
Single Class ◽  
Apparent Dissociation Constant ◽  
Lower Affinity ◽  
A6 Cells ◽  
Nuclear Binding

This study tests the hypothesis, in A6 epithelia, that 1) corticosterone stimulates active Na+ transport (short-circuit current, Isc) by an additional receptor mechanism to the type I (mineralocorticoid) and type II (glucocorticoid) mechanisms shared with aldosterone (Aldo) and 2) that the agonist may be 6 beta-OH-corticosterone made in the effector cell. The dose-response relationship of corticosterone at 24 h resolves into two components, by curve fitting, with a 50% effective concentration (EC50) for 10% of maximum Isc stimulation of 2 X 10(-9) M and an EC50 for the other 90% of 3 X 10(-7) M. The EC50 of the smaller component correlates with the apparent dissociation constant (K'd) of corticosterone for high affinity (type II) nuclear binding sites shared with Aldo. In unlabeled analogue competition studies Aldo and corticosterone displaced nuclear binding equally below 10(-8) M [3H]corticosterone, indicating only shared sites. However, nonshared saturable sites (displaced by corticosterone but not by Aldo) were found at [3H]-corticosterone concentrations above 10(-8) M. Concentration-binding curves performed with [3H]corticosterone, in presence of 1,000 X Aldo to displace shared sites, revealed a single class of binding sites with a half-maximal saturation of 2 X 10(-7) M, which is quite similar to the EC50 of the lower affinity component of Isc stimulation by corticosterone at 24 h. Reversed phase high-pressure liquid chromatography of nuclear extracts indicates that the saturable component of bound [3H] was 6 beta-OH-[3H]corticosterone derived from [3H]corticosterone. Thus, A6 cells metabolize corticosterone to 6 beta-OH-corticosterone, which in turn occupies lower-affinity receptors not shared with Aldo or corticosterone, to mediate most of the active Na+ transport stimulation by corticosterone.

Sign in / Sign up

Export Citation Format

Share Document