Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Transcortin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed1991

A transcortin-binding protein in the plasma membrane of human syncytiotrophoblast.

Using affinity chromatography on immobilized transcortin of 125I-labeled, cholate-solubilized plasma membranes of human syncytiotrophoblast, a transcortin-binding protein with a minimal Mr of about 20 kDa has been isolated. It was found to be a sialoglycoprotein with an isoelectric point at pH 4.4 (about 5.0 after the treatment with neuraminidase). We assume that this protein is a component of membrane recognition system for transcortin-steroid complexes.

Cell Membrane↗
PubMed1983

Evidence for a transcortin-like component in human breast cyst fluid.

The occurrence of a specific glucocorticoid binding activity was investigated in breast cyst fluid (BCF) samples aspirated from 481 women under treatment for breast cystic disease. [3H]cortisol was incubated with BCF at 4 degrees C with and without 100-fold molar excess of non-radioactive steroid in order to account for non-specific binding. Corticosterone, progesterone and dexamethasone-binding activities were also investigated in about 50% of the specimens. Consistent amounts of a specific cortisol-, corticosterone- and progesterone-binding component were observed in about 30% of samples. Apparent binding values ranged from 4.31 to 80.78 nmol/l for cortisol, from 3.94 to 75.72 nmol/l for corticosterone, and from 1.18 to 16.45 nmol/l for progesterone. No specific binding for dexamethasone was detected. Scatchard analyses for [3H]cortisol and [3H]progesterone were made in pools of 'positive' BCF, human serum and whey of human milk, respectively. The mean values of the apparent equilibrium association constant (Ka) were compatible with the existence of high affinity protein-hormone interactions in each considered medium. Data obtained in ligand competition experiments for different steroid molecules suggest the similarity of the glucocorticoid- and progesterone-binding component found in 30% of BCF samples examined with the plasma corticosteroid-binding globulin (CBG, transcortin) and especially with the transcortin-like component detected in the whey of the human milk. It is suggested that the transcortin-like component may play an important role in controlling kinetics of transport and in regulating the effective levels of cortisol and progesterone in numerous breast cyst fluids.

Adult↗
PubMed1983

Phase shifts in circadian rhythmicity of total, free corticosterone and transcortine plasma levels in hypothyroid male Japanese quails.

Control, radiothyroidectomized, and methimasol-treated short day (6L:18D; beginning of light at 0700) male Japanese quails were studied with regard to their circadian rhythmicity of total, free corticosterone and transcortine plasma level. In the controls, the peak of total and free corticosterone coincided with the maximal corticosterone binding capacity of transcortine; these parameters can be characterized by similar daily rhythm. In hypothyroid birds a synchronous phase shift of these parameters has been observed. In methimasol-treated animals the phase shift of the circadian rhythmicity was 6-8 hr, and in the radiothyroidectomized group 12 hr, respectively. According to the degree of hypothyroidism the metabolic clearance rate (MCR) of corticosterone decreased. This effect leads to the phase shift of total corticosterone rhythm, and the shift includes not only free, but also transcortine concentration.

Animals↗
PubMed1983

Cortisol-free transcortin: preparation and effect on mitogen-stimulated lymphocytes.

Human cortisol-free transcortin was prepared from charcoal-treated serum. The major purification was achieved by affinity chromatography on an immunoadsorbent column of transcortin antibodies coupled to Sepharose 4B. A further purification on hydroxylapatite yielded pure transcortin with preserved steroid-binding activity. This preparation had no significant influence on the proliferation of human lymphocytes stimulated with phytohemagglutinin, nor did it increase the inhibition of lymphocyte proliferation by cortisol or dexamethasone.

Adult↗
PubMed1984

Polymerization of human transcortin in plasma.

Using radial immunodiffusion and antiserum raised against purified transcortin, polymers of native transcortin have been identified in plasma. They are characterized by multiple precipitin bands, the size of which diminishes on dilution, consistent with reversibility of this form of polymer. Spectrophotometric scans have been used to study the time course of polymerization in purified transcortin, in which dilution reversibility can be demonstrated also, and in which disaggregation may be produced by addition of sodium dodecyl sulphate and dithiothreitol, but apparently not by cortisol.

Humans↗
PubMed1986

Cortisol 17 beta acid, transcortin, and the heterogeneity of rat brain glucocorticoid receptors.

Binding of tracer or competing steroids to transcortin can compromise specificity studies on receptors for adrenal steroids. Recently Alexis et al. have used cortisol 17 beta acid at high concentrations to prevent steroid binding to any transcortin possibly contaminating rat brain cytosol preparations. On the basis of limited specificity studies of [3H]dexamethasone and [3H]corticosterone binding under such conditions, it was claimed that binding sites for the two steroids are indistinguishable, and it is thus unnecessary to invoke distinct binding sites for each glucocorticoid. We have extended these competition studies in the presence of cortisol 17 beta acid, and shown that in rat hippocampus Type I, corticosterone-preferring glucocorticoid receptors can be clearly distinguished both from transcortin and from Type II, dexamethasone-binding glucocorticoid receptors.

Androstanols↗
PubMed1993

Decreased cortisol-binding affinity of transcortin Leuven is associated with an amino acid substitution at residue-93.

Genomic DNA was isolated from two related individuals who are homozygous for transcortin Leuven, a corticosteroid-binding globulin variant with decreased cortisol-binding affinity. This material was amplified using intron-specific oligonucleotide primers in a polymerase chain reaction to obtain the four exons that encode transcortin. Sequence analysis of these exons showed several mutations within the coding sequence of both individuals, but only one of these will result in an amino acid substitution. This mutation is located within exon 2 and alters the codon (CTC) normally associated with Leu-93 in the transcortin polypeptide to a codon (CAC) for histidine in the variant genes.

Amino Acid Sequence↗
PubMed1984

More HLA haploidentity in pairs of sibs with the same transcortin levels.

In 50 sibships, each comprising at least 2 male sibs, the oldest sib was paired with each of his brothers. All sibs were HLA- haplotyped and their serum transcortin level was determined. The HLA haploidentical pairs were compared with the sibpairs having no HLA haplotype in common. The odds for the haploidentical pairs of having a small difference (less than 0.07 mg per g total serum protein) in serum transcortin was nearly 4 times (3.94; P less than 0.025) greater than for the pairs of brothers having no HLA haplotype in common. This abnormal distribution in HLA haplotypes confirms our previous findings on the relation of certain HLA haplotypes with either high or low basal serum transcortin levels.

Genotype↗
PubMed1976

Heterogeneity of pituitary glucocorticoid binding evidence for a transcortin-like compound.

Scatchard analysis, as well as sucrose gradient centrifugation demonstrate that at least two classes of specific glucocorticoid binding sites occur in the adenohypophysis. One, exhibited high affinity for both corticosterone and dexamethasone (receptor D), while the other bound only corticosterone. The latter binder revealed physico-chemical properties closely similar to those of plasma transcortin, but was shown not to be due to simple blood contamination of cytosol. This transcortin-like (TL) component, however, seemed to be carried over from plasma, since the concentration of pituitary binding sites strikingly paralleled physiological variations of plasma transcortin. Furthermore, experiments carried out with isolated pituitary cells suggested an intracellular location of that binder, although sticking to the cell membrane cannot be excluded. Finally, it was shown that the TL compound was unable, unlike the receptor D, to transfer glucocorticoids into the nuclei. One of its possible roles could be to modulate the interaction between steroids and compound D.

Adrenal Glands↗
PubMed1983

Evidence for the presence of specific binding sites for transcortin in human liver plasma membranes.

Binding sites which recognize and bind specifically asialotranscortin and the native transcortin-cortisol complex have been found in plasma membranes of human liver cells. The native conformation of transcortin is an absolute requirement for the binding reaction of the transcortin-hormone complex. Sex-hormone-binding globulin and thyroxine-binding globulin from human serum do not bind to this binding sites.

Binding Sites↗
PubMed1982

Modification of human transcortin by tetranitromethane. Evidence for the implication of a tyrosine residue in cortisol binding.

The effect of tetranitromethane on the cortisol binding activity of human transcortin has been investigated. This reagent induced a decrease of activity concomitant with nitration of tyrosine residues. An oxidation of sulphydryl groups was also observed but had no implication on cortisol binding. The nitration was specifically oriented in the site at pH6 and with low concentrations of reagent; under these conditions, a single essential tyrosine per molecule of transcortin seems implicated in cortisol binding. The absence of denaturation in modified transcortin was checked by circular dichroism spectra and polyacrylamide gel electrophoresis. Site specificity was demonstrated by full protection with cortisol against inactivation.

Binding Sites↗
PubMedDate not supplied

Cortisol and transcortin in human seminal plasma and amniotic fluid as estimated by modern specific assays.

Cortisol concentrations in human seminal plasma, as estimated by the very specific Amersham 'Amerlite' luminescence immunoassay, were 176 +/- 43 (85-260) nmol/l, that is, 63.7 +/- 15.5 (31-94) ng/ml (mean +/- SD, n = 21). This is about 60% of random levels in blood serum and is the first description of cortisol in seminal fluid. In human amniotic fluid at 16-22 weeks of gestation, cortisol concentrations were lower, at 72.6 +/- 14.6 (63-124) nmol/l, that is, 29.3 +/- 5.3 (23-45) ng/ml (n = 21). Concentrations were about 15% of random maternal serum levels in the second trimester of pregnancy. The cortisol concentrations in both fluids were considerably higher than those reported for saliva, which has a mean of about 10 nmol/l. Transcortin (corticosteroid binding globulin, CBG), has been found in human seminal plasma and amniotic fluid for the first time. Concentrations were low, with values up to 12 micrograms/ml, with no significant difference between the two fluids, when using the IRE-Megenix monoclonal iodinated radioimmunoassay. Transcortin concentrations were about 10% of levels in non-pregnant blood serum, compared with about 0.1% for saliva. The higher concentrations of transcortin could perhaps account for the greater diffusion of cortisol into seminal plasma and amniotic fluid. The presence of beta-endorphin, ACTH and cortisol in amniotic fluid, seminal fluid, ovarian follicular fluid, endometrial fluid and gastric fluid may possibly, indicate the existence of a small paracrine ACTH-cortisol axis in the relevant secretory tissues.

Amniotic Fluid↗
PubMed1983

Response of transcortin and alpha 2u-globulin to turpentine-induced inflammation in the rat: influence of corticosteroids and prolactin.

Evidence is presented that (transcortin and alpha 2u-globulin react as negative acute-phase proteins in the rat. Thirty-six hours after turpentine injection, the serum concentration of these proteins showed a two- to threefold decrease. Thereafter, transcortin rapidly returned to normal values, whereas alpha 2u-globulin remained low. This reaction pattern was still present after adrenalectomy, adrenalectomy and administration of glucocorticoids, and after treatment with bromocriptine, a suppressor of prolactin secretion. It is concluded that changes in the secretion of glucocorticoids and prolactin are not required for the observed turpentine-induced decrease of transcortin and alpha 2u-globulin.

Adrenalectomy↗
PubMedDate not supplied

[Binding ability of rat transcortin after adrenalectomy].

High performance liquid chromatography was used to determine corticosterone concentration and transcortin binding capacity (TBC) in blood plasma of rats with bilateral adrenalectomy, before and after removal of endogenous hormones within 7 days (0.4, 0.2, 1, 2, 3, 4, 5, 7 days). During the first day TBC significantly decreased. However, concentration of protein binding sites subsequently elevated exceeding 2-fold the level of control values within the 7th day of the experiment. Concentration of 14C-immunoreactive transcortin in rat liver cytosol did not differ from control levels on the 5th day after the adrenalectomy. The adrenalectomy did not affect the transcortin affinity constant for corticosterone. These data suggest that the increased rate of blood plasma TBC was not related to activation of liver specific protein biosynthesis.

Adrenal Glands↗
PubMed1991

[Transcortin in rat kidney tissue: distribution in microsomal fractions].

During chromatography of renal tissue cytosolic proteins on DEAE-cellulose the protein specifically binding [3H]corticosterone is eluted within the potassium phosphate concentration range of 0.08-0.10 M. Analysis of kidney slices revealed the synthesis of [3H]transcortin whose electrophoretic mobility was close to that of the blood plasma protein. Using radioimmunochemical methods, it has been found that transcortin-specific [125I]IgG antibodies interact with growing polypeptide chains of membrane-bound polyribosomes. Free polyribosomes do not bind antibodies against transcortin.

Animals↗
PubMed1988

[Interaction of the transcortin-progesterone complex with plasma membranes of human decidual epithelium].

It was demonstrated that transcortin complexed with progesterone specifically binds to plasma membranes of human decidual endometrium, a progesterone target tissue. This interaction is characterized by a high affinity [Kd = (1.0 +/- 0.2).10(-10) mol/l] and selectivity. Such human serum proteins as albumin, orosomucoid, transferrin, thyroxine- and sex steroid-binding globulins do not compete with transcortin for the binding sites on the membranes. The concentration of endogenous transcortin in sodium cholate-solubilized endometrium cell membranes was determined by the radioimmunoassay method.

Binding, Competitive↗
PubMed1979

Effect of testosterone and thyroxine on corticosterone and transcortine plasma levels in different bird species.

Effect of testosterone and thyroxine on corticosterone and transcortine plasma levels has been investigated in photostimulated (18L--6D) Peking duck, domestic pigeon, Japanese quail and cock. In all these bird species corticosterone and transcortine plasma levels increased following castration, while restitution with testosterone decreased them in the castrated animals. Thyroidectomy and thyroxine supplements in thyroidectomized birds failed to influence plasma corticosterone and, apart from cock, transcortine levels. It is suggested that in case of high testosterone levels the effect of thyroid hormones on the function of the adrenal cortex can partly or completely be masked by the dominancy of the testocorticoid interrelation.

Animals↗
PubMed1984

Use of monoclonal antibodies in a radioimmunoassay for human transcortin.

We describe the production of monoclonal antibodies to human transcortin and their use in a radioimmunoassay (RIA). A high-affinity antibody (Ka = 4 X 10(10) L/mol) made possible a sensitive RIA for transcortin (detection limit = 0.23 ng per tube), whereas use of an antibody of moderate affinity (Ka = 5 X 10(8) L/mol) was more suitable for the routine measurement of transcortin in serum, only a 25-fold dilution of the sample being required instead of 1500-fold. The correlation was good between both RIAs (r = 0.959) and between each of the RIAs and radial immunodiffusion (r = 0.955 and 0.976 for the methods with high- and low-affinity antibody, respectively). Although monoclonal antibodies were used in the RIAs and polyclonal ones in the radial immunodiffusion procedure, similar values were obtained by all techniques.

Adult↗