scholarly journals Oestrogen-induced synthesis of thiamin-binding protein in immature chicks. Kinetics of induction, hormonal specificity and modulation

1980 ◽  
Vol 186 (1) ◽  
pp. 201-210 ◽  
Author(s):  
Kalappagowda Muniyappa ◽  
P. Radhakantha Adiga

A specific radioimmunoassay procedure was developed to monitor the plasma concentrations of thiamin-binding protein, a minor yolk constituent of the chicken egg. By using this sensitive assay, the kinetics of oestrogen-induced elaboration of this specific protein in immature chicks was investigated. After a single injection of the steroid hormone, with an initial lag period of 4–5h the thiamin-binding protein rapidly accumulated in the plasma, attaining peak concentrations around 75h and declining thereafter. A 4-fold amplification of the response was noticed during the secondary stimulation, and this increased to 9-fold during the tertiary stimulation with the steroid hormone. The magnitude of the response was dependent on the hormone dose, and the initial latent period and the duration of the ascending phase of induction were unchanged for the hormonal doses tested during both the primary and secondary stimulations. The circulatory half-life of the protein was 6h as calculated from the measurement of the rate of disappearance of the exogenously administered 125I-labelled protein. Simultaneous administration of progesterone, dihydrotestosterone or corticosterone did not alter the pattern of induction. On the other hand, hyperthyroidism markedly decreased the oestrogenic response, whereas propylthiouracil-induced hypothyroidism had the opposite effect. The anti-oestrogen E- and Z-clomiphene citrates, administered 30min before oestrogen, effectively blocked the hormonal induction. α-Amanitin and cycloheximide administered along with or shortly after the sex steroid severely curtailed the protein elaboration. A comparison of the kinetics of induction of thiamin- and riboflavin-binding proteins by oestrogen revealed that, beneath an apparent similarity, a clear-cut difference exists between the two vitamin-binding proteins, particularly with regard to hormonal dose-dependent sensitivity of induction and the half-life in circulation. The steroid-mediated elaboration of the two yolk proteins thus appears to be not strictly co-ordinated, despite several common regulatory features underlying their induction.

1988 ◽  
Vol 116 (2) ◽  
pp. 191-200 ◽  
Author(s):  
T. H. Elsasser ◽  
T. S. Rumsey ◽  
A. C. Hammond ◽  
R. Fayer

ABSTRACT A parasitic disease model (sarcocystosis) was used to study the effects of infection and associated plane of nutrition on GH and somatomedin-C (SM-C) patterns in plasma, and SM-C binding protein patterns in plasma from 4-month-old male Holstein calves. Calves, matched by age and rate of growth before the experiment, were divided into three treatment groups (n = 7). In the first (control), animals were uninfected and food was available ad libitum; in the second, animals were infected with Sarcocystis cruzi and food was available ad libitum. The third group consisted of uninfected animals pair-fed to the level of feed intake of the infected animals. Blood samples were obtained at various times after infection for analysis of the secretory patterns of GH (day 27 after infection, samples every 10 min for 6 h), SM-C (days 27, 35 and 58 after infection) or binding protein (day 42 after infection). Samples were analysed for GH and SM-C by radioimmunoassay. Relative molecular weights of binding proteins were assessed by elution patterns from gel permeation columns. Clinical signs of infection were manifest abruptly on day 26 after infection. Voluntary feed intakes of infected calves as a per cent of control calves were 18, 46 and 78 on days 27, 35 and 58 after infection respectively. Plasma GH concentrations were lower in infected and pair-fed than in control calves (P < 0·05). Plasma SM-C concentrations were reduced in calves with diminished feed intakes and lower still in infected calves (P < 0·05). Plasma SM-C was positively correlated with nitrogen retention across treatment groups (r = 0·81). Two classes of binding proteins differing in molecular weight were identified. The relative amounts of each binding protein in plasma were reduced during low feed intake with some differences in the endogenous saturation affected by infection. These data suggest that altered growth and metabolism in parasitized calves may arise in part from both nutritional and infection-mediated effects on the regulation of GH, SM-C and SM-C binding proteins. J. Endocr. (1988) 116, 191–200


2005 ◽  
Vol 11 (20) ◽  
pp. 7354-7361 ◽  
Author(s):  
Mahmut Yasen ◽  
Kazunori Kajino ◽  
Sayaka Kano ◽  
Hiroshi Tobita ◽  
Junji Yamamoto ◽  
...  

1976 ◽  
Vol 157 (2) ◽  
pp. 395-400 ◽  
Author(s):  
H B White ◽  
B A Dennison ◽  
M A Della Fera ◽  
C J Whitney ◽  
J C McGuire ◽  
...  

1. Biotin in chicken egg yolk is non-covalently bound to a specific protein that comprises 0.03% of the total yolk protein (0.8 mg/yolk). This biotin-binding protein is not detectable by the normal avidin assay owing to the biotin being tightly bound. Exchange of [14C]biotin for bound biotin at 65 degrees C is the basis of an assay for this protein. 2. Biotin-binding protein from egg yolk is distinguishable from egg-white avidin on Sephadex G-100 gel filtration, although the sizes of the two proteins appear quite similar. 3. Biotin-binding protein is denatured at a lower temperature and freely exchanges biotin at lower temperatures than does avidin. 4. The biotin-binding protein in egg yolk is postulated to be responsible for the deposition of biotin in egg yolk. D-[carboxyl-14C]Biotin injected into laying hens rapidly appears in the egg bound to yolk biotin-binding protein and avidin. Over 60% of the radioactivity is eventually deposited in eggs. The kinetics of biotin deposition in the egg suggests a 25 day half-life for an intracellular biotinyl-coenzyme pool in the laying hen.


1999 ◽  
Vol 55 (11) ◽  
pp. 1850-1857 ◽  
Author(s):  
Barnali Neel Chaudhuri ◽  
Gerard J. Kleywegt ◽  
Isabelle Broutin-L'Hermite ◽  
Terese Bergfors ◽  
Hans Senn ◽  
...  

Retinoids play important roles in diverse cellular processes including growth, cell differentiation and vision. Many natural and synthetic retinoids are used as drugs in dermatology and oncology. A large amount of data has been accumulated on the cellular activity of different synthetic retinoids. They are stabilized and transported inside the cell cytoplasm by binding and transport proteins, such as cellular retinol-binding proteins and cellular retinoic acid binding proteins (CRABPs). The structures of human CRABP II in complex with two different synthetic retinoids, Ro13-6307 and Ro12-7310 (at 2.1 and 2.0 Å resolution, respectively) and of bovine CRABP I in complex with a retinobenzoic acid, Am80 (at 2.8 Å resolution) are described. The binding affinities of human CRABP I and II for the retinoids studied here have been determined. All these compounds have comparable binding affinities (nanomolar range) for both CRABPs. Apart from the particular interactions of the carboxylate group of the retinoids with specific protein groups, each structure reveals characteristic interactions. Studying the atomic details of the interaction of retinoids with retinoid-binding proteins facilitates the understanding of the kinetics of retinoid trafficking inside the cytoplasm.


2003 ◽  
Vol 278 (42) ◽  
pp. 41093-41098 ◽  
Author(s):  
Stephen R. Shouldice ◽  
Douglas R. Dougan ◽  
Pamela A. Williams ◽  
Robert J. Skene ◽  
Gyorgy Snell ◽  
...  

1990 ◽  
Vol 271 (3) ◽  
pp. 661-666 ◽  
Author(s):  
L E Kelly

Recent reports have shown that there exists in mammalian brain a number of heat-stable Ca2(+)-binding proteins that are distinct from calmodulin [McDonald & Walsh (1985) Biochem. J. 232, 559-567]. We have attempted to characterize equivalent Ca2(+)-binding proteins from Drosophila. Affigel-phenothiazine chromatography, which can be used to purify calmodulin and other Ca2(+)-binding proteins, allowed the identification of a possible heat-stable 23 kDa Ca2(+)-binding protein. A purification procedure for this protein has been devised. Purified 23 kDa protein shows characteristics typical of a Ca2(+)-binding protein; there is a mobility shift on SDS/polyacrylamide gels in the presence of EGTA, and Western blotting, followed by the use of the 45Ca2+ overlay technique, confirms that the 23 kDa protein does bind Ca2+. 45Ca2+ binding studies indicate that this protein binds 1 mol of Ca2+/mol of protein, with Kd 1.9 microM. A single band with pI 5.2 is obtained on isoelectric focusing. Analysis of Western blots of Drosophila tissues probed with antibodies to the Ca2(+)-binding protein indicates that it has a widespread distribution, but is absent from muscle tissue. The antibodies also cross-react with a protein of identical molecular mass in extracts of sheep brain. The possible similarity between this Drosophila Ca2(+)-binding protein and mammalian proteins is discussed, and comparison is made between this Drosophila protein and other Ca2(+)-binding proteins purified from vertebrates.


1987 ◽  
Author(s):  
V Bode ◽  
R Franz ◽  
D Welzel ◽  
H Wolf ◽  
C Harenberg

Low molecular weight (LMW) heparin is characterized by a higher affinity to antithrombin HI, less inhibition of thrombin and increased inhibition of factor Xa. The half life of the antifactor Xa activity of LMW heparin is doubled compared to normal heparin. However, these parameters reflect the pharmacodynamics rather than the kinetic of the compound. We, therefore, analyzed the kinetics of LMW heparin after i.v. injection in man using protamine chloride for gravimetric evaluation of LMW heparin in the plasma samples.Six healthy adults received 100 units per kg body weight normal heparin or 100 anti Xa units per kg LMW heparin (Sandoz AG, Niimberg, FRG). To serial samples of venous blood protamine chloride was added in serial dilutions until the thrombin inhibition was antagonized. Since factor Xa inhibition of LMW heparin cannot be abolished completely by protamine chloride, two amounts of protamine chloride were added to the plasma samples ex vivo, until factor Xa was inhibited up to 0,2 and 0,04 units/ml. The following maximal plasma concentrations (C max) and half lives (T/2) were calculated (average values):The pharmacokinetics of normal heparin show no differences on thrombin and factor Xa interaction. LMW heparin, however, interacts to 30 % with thrombin and to 100 % with factor Xa; the half life on factor Xa is twice as long as on thrombin; releases endogenous compounds with antifactor Xa activity, which are neutralized only hardly by protamine chloride;and these endogenous compounds mediate in part the longer half life.


2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Harvey C. Gonick

Lead-binding proteins are a series of low molecular weight proteins, analogous to metallothionein, which segregate lead in a nontoxic form in several organs (kidney, brain, lung, liver, erythrocyte). Whether the lead-binding proteins in every organ are identical or different remains to be determined. In the erythrocyte, delta-aminolevulinic acid dehydratase (ALAD) isoforms have commanded the greatest attention as proteins and enzymes that are both inhibitable and inducible by lead. ALAD-2, although it binds lead to a greater degree than ALAD-1, appears to bind lead in a less toxic form. What may be of greater significance is that a low molecular weight lead-binding protein, approximately 10 kDa, appears in the erythrocyte once blood lead exceeds 39 μg/dL and eventually surpasses the lead-binding capacity of ALAD. In brain and kidney of environmentally exposed humans and animals, a cytoplasmic lead-binding protein has been identified as thymosinβ4, a 5 kDa protein. In kidney, but not brain, another lead-binding protein has been identified as acyl-CoA binding protein, a 9 kDa protein. Each of these proteins, when coincubated with liver ALAD and titrated with lead, diminishes the inhibition of ALAD by lead, verifying their ability to segregate lead in a nontoxic form.


2007 ◽  
Vol 27 (18) ◽  
pp. 6469-6483 ◽  
Author(s):  
John L. Goodier ◽  
Lili Zhang ◽  
Melissa R. Vetter ◽  
Haig H. Kazazian

ABSTRACT LINE-1 retrotransposons constitute one-fifth of human DNA and have helped shape our genome. A full-length L1 encodes a 40-kDa RNA-binding protein (ORF1p) and a 150-kDa protein (ORF2p) with endonuclease and reverse transcriptase activities. ORF1p is distinctive in forming large cytoplasmic foci, which we identified as cytoplasmic stress granules. A phylogenetically conserved central region of the protein is critical for wild-type localization and retrotransposition. Yeast two-hybrid screens revealed several RNA-binding proteins that coimmunoprecipitate with ORF1p and colocalize with ORF1p in foci. Two of these proteins, YB-1 and hnRNPA1, were previously reported in stress granules. We identified additional proteins associated with stress granules, including DNA-binding protein A, 9G8, and plasminogen activator inhibitor RNA-binding protein 1 (PAI-RBP1). PAI-RBP1 is a homolog of VIG, a part of the Drosophila melanogaster RNA-induced silencing complex (RISC). Other RISC components, including Ago2 and FMRP, also colocalize with PAI-RBP1 and ORF1p. We suggest that targeting ORF1p, and possibly the L1 RNP, to stress granules is a mechanism for controlling retrotransposition and its associated genetic and cellular damage.


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