scholarly journals A high-affinity cytosol binding protein for 1 α,25-dihydroxycholecalciferol in the uterus of Japanese quail

1980 ◽  
Vol 190 (3) ◽  
pp. 513-518 ◽  
Author(s):  
N Takahashi ◽  
E Abe ◽  
R Tanabe ◽  
T Suda
Keyword(s):  
Dissociation Constant ◽  
Japanese Quail ◽  
Egg Laying ◽  
Target Organ ◽  
Nuclear Fraction ◽  
Temperature Dependent ◽  
Cytosol Fraction ◽  
High Affinity ◽  
Uterine Mucosa ◽  
Fold Excess

Cytosol fractions prepared from the uterine mucosa of egg-laying Japanese Quail were analysed for binding of the metabolites of cholecalciferol. When the uterus was incubated at 37 degrees C with various radioactive metabolites of cholecalciferol, the nuclear fraction incorporated only 1 alpha,25-dihydroxy[3H]cholecalciferol. When the uterus was incubated at 0 degree C with 1 alpha,25-dihydroxy[3H]cholecalciferol, most of the radioactivity was found in the cytosol. Translocation of 1 alpha,25-dihydroxy[3H]cholecalciferol from the cytosol to the nucleus was temperature-dependent. The addition of 100-fold excess amounts of unlabelled 1 alpha-25-dihydroxycholecalciferol significantly diminished the nuclear binding of 1 alpha,25-dihydroxy[3H]cholecalciferol. The cytosol fraction contained a 3.5 S macromolecule that specifically binds 1 alpha,25-dihydroxy[3H]cholecalciferol. The dissociation constant was 0.39 nM and the maximal binding was 55 fmol/mg of protein. These results strongly suggest that the uterus in egg-laying birds is a target organ or 1 alpha,25-dihydroxycholecalciferol.

PARATHYROID HORMONE AND EGGSHELL CALCIFICATION IN JAPANESE QUAIL

1976 ◽  
Vol 71 (2) ◽  
pp. 239-243 ◽  
Author(s):  
C. G. DACKE
Keyword(s):  
Parathyroid Hormone ◽  
Japanese Quail ◽  
Unit Area ◽  
Egg Laying ◽  
Target Organ ◽  
Shell Weight ◽  
Parathyroid Extract ◽  
Egg Shell ◽  
Subsequent Incorporation

SUMMARY The effect of parathyroid hormone (PTH) on egg-shell calcification has been investigated in egg-laying Japanese quail. Lilly parathyroid extract (PTE) when injected into quail within 2–6 h of oviposition caused a significantly increased deposition of a chronic 45Ca label into the sequential egg-shell compared with the previous egg in the clutch, indicating increased mobilization of bone Ca and its subsequent incorporation into the egg-shell. At the same time egg-shell weight/unit area and egg-shell Ca/unit area were significantly decreased. Parathyroid extract injected 12–16 h after oviposition had none of these effects. Purified PTH also caused a significant decrease in egg-shell weight/unit area if injected within 2–6 h of oviposition. This result indicated an action of PTH either directly or indirectly on the avian oviduct limiting egg-shell calcification. The loss of responses in the 12–16 h treated birds may reflect high endogenous PTH levels with subsequent saturation of target organ receptors.

The Binding of Calcium Ions to Bovine Factor X by Rate Dialysis

1978 ◽  
Vol 40 (02) ◽  
pp. 350-357
Author(s):  
Robert H Yue ◽  
Menard M Gertler
Keyword(s):  
Molecular Weight ◽  
Dissociation Constant ◽  
Calcium Ions ◽  
Activation Process ◽  
Factor X ◽  
The Real ◽  
High Affinity ◽  
Binding Data ◽  
Sequential Mechanism ◽  
Bovine Factor

SummaryThe binding of Ca+2 to bovine factor X (molecular weight of 74,000) (Yue und Gertler 1977) was studied by the technique of rate dialysis and with the use of 45Ca+2. The binding data are consistent with a model of sequential mechanism. One mole of Ca+2 binds to the glycoprotein with a dissociation constant of 5.2 × 10-5 M and an additional 39 ± 4 moles of Ca+2 bind to this zymogen with a dissociation constant of 3.7 × 10-3M. The binding of the high affinity Ca+2 causes a functionally significant change in the zymogen, and (calcium) (factor X) complex is the real substrate in the activation process by the protease in Russell’s viper venom.

scholarly journals Effects of constant incubation regimes on eggs and hatchlings of the egg-laying skink, Oligosoma suteri

2021 ◽  
Author(s):  
◽  
Kelly Maree Hare
Keyword(s):  
Hatching Success ◽  
Incubation Temperature ◽  
Unit Length ◽  
Condition Index ◽  
Egg Laying ◽  
Maternal Influence ◽  
Temperature Dependent ◽  
Sprint Speed ◽  
Fitness Traits ◽  
Incubation Temperatures

<p>The conditions under which reptilian eggs are incubated affect survival probability and physiological attributes of the progeny. The egg-laying skink, Oligosoma suteri, is the only endemic oviparous lizard in New Zealand. No controlled laboratory incubation had previously been undertaken, and thus no information was available on the requirements for successful captive incubation. I studied the effects of incubation regime on the eggs and hatchlings of O. suteri to four months of age. Oligosoma suteri eggs (n = 174) were randomly distributed among three constant incubation temperatures (18°C, 22°C and 26°C) and two water potentials (-120 kPa and -270 kPa). Hatching success and hatchling survival were greatest at 22°C and 26°C, with hatchlings from 18°C incubation suffering from physical abnormalities. Incubation regime and maternal influence did not affect sex of individuals, with equal sex ratios occurring from each incubation treatment. Hatchlings from the 22°C and -120 kPa incubation treatments were larger, for most measurements, and warmer incubation temperatures resulted in increased growth rates. Juveniles from 22°C and 26°C and individuals with greater mass per unit length (condition index) sprinted faster over 0.25 m. Sprint speed was positively correlated with ambient temperature. At four months of age sprint speed decreased in 18°C individuals and individuals incubated at 26°C and -270 kPa compared to their performance at one month. The results suggest that the most successful captive incubation regime for O. suteri is 22°C and -120 kPa. This study also shows that temperature-dependent sex determination does not occur in O. suteri, but that fitness traits are influenced by incubation temperature.</p>

scholarly journals Competitive displacement of full-length HIV-1 Nef from the Hck SH3 domain by a high-affinity artificial peptide

2007 ◽  
Vol 388 (6) ◽  
pp. 611-615 ◽  
Author(s):  
Thomas Stangler ◽  
Tuyen Tran ◽  
Silke Hoffmann ◽  
Holger Schmidt ◽  
Esther Jonas ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Phage Display ◽  
Dissociation Constant ◽  
Sh3 Domain ◽  
Competitive Displacement ◽  
Ligand Interaction ◽  
High Affinity ◽  
Hematopoietic Cell Kinase ◽  
Proline Rich Peptide ◽  
Hiv 1

AbstractWe studied the interaction of the artificial 12-aa proline-rich peptide PD1 with the SH3 domain of the hematopoietic cell kinase Hck and the peptide's potency in competitively displacing HIV-1 Nef from the Hck SH3 domain. PD1 was obtained from a phage display screen and exhibits exceptional affinity for the Hck SH3 domain (Kd=0.23 μM). Competition experiments using NMR spectroscopy demonstrate that the peptide even displaces Nef from Hck SH3 and allow for estimation of the Nef-Hck SH3 dissociation constant (Kd=0.44 μM), the strongest SH3 ligand interaction known so far. Consequences of this study for novel antiviral concepts are discussed.

scholarly journals Unexpected resilience of species with temperature-dependent sex determination at the Cretaceous–Palaeogene boundary

2010 ◽  
Vol 7 (2) ◽  
pp. 295-298 ◽  
Author(s):  
Sherman Silber ◽  
Jonathan H. Geisler ◽  
Minjin Bolortsetseg
Keyword(s):  
Climate Change ◽  
Sex Ratio ◽  
Sex Determination ◽  
Volcanic Eruptions ◽  
Egg Laying ◽  
Molecular Clocks ◽  
Temperature Dependent ◽  
Hell Creek Formation ◽  
Male Preponderance ◽  
Genotypic Sex Determination

It has been suggested that climate change at the Cretaceous–Palaeogene (K–Pg) boundary, initiated by a bolide impact or volcanic eruptions, caused species with temperature-dependent sex determination (TSD), including dinosaurs, to go extinct because of a skewed sex ratio towards all males. To test this hypothesis, the sex-determining mechanisms (SDMs) of Cretaceous tetrapods of the Hell Creek Formation (Montana, USA) were inferred using parsimony optimizations of SDMs on a tree, including Hell Creek species and their extant relatives. Although the SDMs of non-avian dinosaurs could not be inferred, we were able to determine the SDMs of 62 species; 46 had genotypic sex determination (GSD) and 16 had TSD. The TSD hypothesis for extinctions performed poorly, predicting between 32 and 34 per cent of survivals and extinctions. Most surprisingly, of the 16 species with TSD, 14 of them survived into the Early Palaeocene. In contrast, 61 per cent of species with GSD went extinct. Possible explanations include minimal climate change at the K–Pg, or if climate change did occur, TSD species that survived had egg-laying behaviour that prevented the skewing of sex ratios, or had a sex ratio skewed towards female rather than male preponderance. Application of molecular clocks may allow the SDMs of non-avian dinosaurs to be inferred, which would be an important test of the pattern discovered here.

scholarly journals Semenogelins I and II bind zinc and regulate the activity of prostate-specific antigen

2005 ◽  
Vol 387 (2) ◽  
pp. 447-453 ◽  
Author(s):  
Magnus JONSSON ◽  
Sara LINSE ◽  
Birgitta FROHM ◽  
Åke LUNDWALL ◽  
Johan MALM
Keyword(s):  
Enzymatic Activity ◽  
Dissociation Constant ◽  
Prostate Specific Antigen ◽  
Protease Activity ◽  
Specific Antigen ◽  
Active State ◽  
Chromogenic Substrate ◽  
Nmr Analysis ◽  
High Concentration ◽  
High Affinity

In semen, the gel proteins SgI and SgII (semenogelins I and II) are digested by PSA (prostate-specific antigen), resulting in liquefaction and release of motile spermatozoa. Semen contains a high concentration of Zn2+, which is known to inhibit the protease activity of PSA. We characterized the binding of Zn2+ to SgI and SgII and found evidence that these proteins are involved in regulating the activity of PSA. Intact SgI and SgII and synthetic semenogelin peptides were used in the experiments. Binding of Zn2+ was studied by radioligand blotting, titration with a zinc (II) fluorophore chelator and NMR analysis. A chromogenic substrate was used to measure the enzymatic activity of PSA. SgI and SgII bound Zn2+ with a stoichiometry of at least 10 mol (mol of protein)−1 and with an average dissociation constant of approx. 5 μM per site. Moreover, Zn2+-inhibited PSA was activated by exposure to SgI or SgII. Since both proteins have high affinity for Zn2+ and are the dominating proteins in semen, they probably represent the major Zn2+ binders in semen, one function of which may be to regulate the activity of PSA. The system is self-regulating, and PSA is maintained in an active state by its substrate.

scholarly journals High-affinity receptor-mediated internalization and degradation of interleukin 2 in human T cells.

1986 ◽  
Vol 163 (3) ◽  
pp. 550-562 ◽  
Author(s):  
M Fujii ◽  
K Sugamura ◽  
K Sano ◽  
M Nakai ◽  
K Sugita ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Lines ◽  
Interleukin 2 ◽  
Culture Fluid ◽  
Type I ◽  
Temperature Dependent ◽  
High Affinity ◽  
Human T Cell ◽  
Human T Cells ◽  
High Affinity Receptor

Receptor-mediated internalization and degradation of IL-2 were investigated in cell lines carrying human T cell leukemia/lymphoma (lymphotrophic) virus type I (HTLV-I) and PHA-treated normal PBL. The HTLV-I-carrying cell lines ILT-Yan and TL-Mor, and the PBL expressed both high- and low-affinity IL-2-R. However, another HTLV-I-carrying T cell line, MT-1, expressed mainly low-affinity receptors. Greater than 50% of the IL-2 bound to high-affinity receptors was internalized within 10 min when these cells were incubated at 37 degrees C. The internalized IL-2 was rapidly degraded and the products were excreted into the culture fluid. The t1/2 of IL-2 degradation in these cells was estimated as 60-80 min at 37 degrees C. The internalization and degradation of IL-2 were both temperature dependent. Light-microscopic autoradiography with 3H-labeled IL-2 confirmed the internalization of IL-2, and suggested that some IL-2 might be carried to the nucleus.

scholarly journals The binding of [3H]adenosine to synaptosomal and other preparations from the mammalian brain

1981 ◽  
Vol 194 (2) ◽  
pp. 611-620 ◽  
Author(s):  
M E Newman ◽  
J Patel ◽  
H McIlwain
Keyword(s):  
Binding Site ◽  
Adenosine Deaminase ◽  
Binding Capacity ◽  
Receptor Site ◽  
Mammalian Brain ◽  
Affinity Binding ◽  
Temperature Dependent ◽  
High Affinity ◽  
High Affinity Site ◽  
Uptake Process

1. A high-affinity adenosine-binding site with Kd(adenosine) 0.5-1.3 microM was demonstrated in particulate and synaptosomal fractions isolated from the cerebral cortex of guinea pig, rat and ox. 2. Binding of [3H]adenosine to this site was inhibited by theophylline and by 2-chloroadenosine, but not by four other adenosine analogues. 3. Endogenous adenosine, found to be present in some preparations at approx. 1 pmol/mg of protein, diminished the binding capacity of the preparations for [3H]adenosine. 4. Addition of the adenosine deaminase inhibitor erythro-9-[1-(1-hydroxyethyl)heptyl]-adenine revealed the presence of a second lower affinity binding site with Kd (adenosine) 5-9 microM and a higher maximal adenosine-binding capacity. The inhibitor partially blocked binding to the high-affinity site in preparations from which adenosine deaminase had been removed by washing. 5. To preparations of particulate fractions maintained under iso-osmotic conditions, adenosine attachment was non-saturable and temperature-dependent, indicating the existence of an active uptake process. 6. The location and binding constant of the high-affinity adenosine-binding site suggest that it corresponds to the receptor site for adenosine-activated adenylate cyclase.

scholarly journals Structural Similarities between Glutamate Receptor Channels and K+ Channels Examined by Scanning Mutagenesis

2001 ◽  
Vol 117 (4) ◽  
pp. 345-360 ◽  
Author(s):  
Victor A. Panchenko ◽  
Carla R. Glasser ◽  
Mark L. Mayer
Keyword(s):  
Dissociation Constant ◽  
Glutamate Receptors ◽  
Selectivity Filter ◽  
Periodic Pattern ◽  
K Channels ◽  
High Affinity ◽  
Aromatic Cage ◽  
Voltage Dependent ◽  
Complete Disruption ◽  
A Site

The pores of glutamate receptors and K+ channels share sequence homology, suggesting a conserved secondary structure. Scanning mutagenesis with substitution of alanine and tryptophan in GluR6 channels was performed based on the structure of KcsA. Our assay used disruption of voltage-dependent polyamine block to test for changes in the packing of pore-forming regions. Alanine scanning from D567 to R603 revealed reduced rectification resulting from channel block in two regions. A periodic pattern from F575 to M589 aligned with the pore helix in KcsA, whereas a cluster of sensitive positions around Q590, a site regulated by RNA editing, mapped to the selectivity filter in KcsA. Tryptophan scanning from D567 to R603 revealed similar patterns, but with a complete disruption of spermine block for 7 out of the 37 positions and a pM dissociation constant for Q590W. Molecular modeling with KcsA coordinates showed that GluR6 pore helix mutants disrupting polyamine block pack against M1 and M2, and are not exposed in the ion channel pore. In the selectivity filter, tryptophan creates an aromatic cage consistent with the pM dissociation constant for Q590W. A scan with glutamate substitution was used to map the cytoplasmic entrance to the pore based on charge neutralization experiments, which established that E594 was uniquely required for high affinity polyamine block. In E594Q mutants, introduction of glutamate at positions S593–L600 restored polyamine block at positions corresponding to surface-exposed residues in KcsA. Our results reinforce proposals that the pore region of glutamate receptors contains a helix and pore loop analogous to that found in K+ channels. At the cytoplasmic entrance of the channel, a negatively charged amino acid, located in an extended loop with solvent-exposed side chains, is required for high affinity polyamine block and probably attracts cations via a through space electrostatic mechanism.

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