Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proto-oncogene c-Kit, a transmembrane receptor tyrosine kinase, is an important regulator of cell growth whose constitutively active oncogenic counterpart, v-kit, induces sarcomas in cats. Mutations in murine c-kit that reduce the receptor tyrosine kinase activity cause deficiencies in the migration and proliferation of melanoblasts, hematopoietic stem cells, and primordial germ cells. We therefore investigated whether c-Kit regulates normal human melanocyte proliferation and plays a role in melanomas. We show that normal human melanocytes respond to mast cell growth factor (MGF), the Kit-ligand that stimulates phosphorylation of tyrosyl residues in c-Kit and induces sequential phosphorylation of tyrosyl residues in several other proteins. One of the phosphorylated intermediates in the signal transduction pathway was identified as an early response kinase (mitogen-activated protein [MAP] kinase). Dephosphorylation of a prominent 180-kDa protein suggests that MGF also activates a phosphotyrosine phosphatase. In contrast, MGF did not induce proliferation, the cascade of protein phosphorylations, or MAP kinase activation in the majority of cells cultured from primary nodular and metastatic melanomas that grow independently of exogenous factors. In the five out of eight human melanoma lines expressing c-kit mRNAs, c-Kit was not constitutively activated. Therefore, although c-Kit-kinase is a potent growth regulator of normal human melanocytes, its activity is not positively associated with malignant transformation.
Mol Biol Cell 1992 Feb
PMID:c-Kit-kinase induces a cascade of protein tyrosine phosphorylation in normal human melanocytes in response to mast cell growth factor and stimulates mitogen-activated protein kinase but is down-regulated in melanomas. 137 24

A new algorithm for creating diverse, irregular and physically reasonable three-dimensional linear atomic chains is described. The linear chains of atoms, or molecular graphs, are generated by solving a series of trigonometric equations within geometric constraints for a given set of atom types. The nature and number of the chains that are produced can be controlled by changing the palette of atom types, so that a chemist user could generate template suggestions that are synthetically relevant to a drug design project. Testing has shown that the method is sufficiently robust to be used in a general context. The molecular graphs could serve as useful structural templates for joining up regions in an active site where a ligand might interact strongly with the receptor. This paper is concerned with the description and proof of the methodology. The approach will form part of a larger structural tool kit for helping chemists to design novel ligands for a specified site.
J Mol Graph 1992 Sep
PMID:Automated site-directed drug design: a method for the generation of general three-dimensional molecular graphs. 146 30

This paper describes an original dot-enzyme-linked immunosorbent assay (ELISA) for predicting ovulation in women, based on the detection of the pre-ovulatory estrogen peak in urine. A monoclonal anti-estrogen antibody is used which recognizes not only free estrogens but also some of their urinary metabolites (17-glucuro- and sulfo-conjugates) allowing a direct assay on early morning urines. Antigen is immobilized as a spot on a nitrocellulose membrane which is immersed in urine in the presence of this antibody. A peroxidase-labeled second antibody allows the detection of the first antibody bound to the membrane. Antigen and anti-estrogen antibody concentrations are chosen to obtain a maximal enzymatic coloration of spots corresponding to basal urinary estrogen levels and no coloration corresponding to the pre-ovulatory surge. Six menstrual cycles were studied, comparing dot-ELISA results with patterns of: (1) urinary estrogens measured by RIA either directly or after hydrolysis and extraction, and (2) basal body temperatures. The validity of the pre-ovulatory signal obtained and the requirements for an adaptation of this methodology to a reliable home kit are discussed.
J Steroid Biochem Mol Biol 1992 Apr
PMID:A direct dot-enzyme immunoassay to detect human ovulation. 156 85

The actions of ACTH on the adrenal cortex are known to be 2-fold. In addition to increased steroidogenesis, ACTH also causes marked vasodilation, reflected by an increased rate of blood flow through the gland. Our studies, using the in situ isolated perfused rat adrenal preparation, have shown that zona fasciculata function and corticosterone secretion are closely related to vascular events, with an increase in perfusion medium flow rate causing an increase in corticosterone secretion, in the absence of any known stimulant. These observations give rise to two important questions: how does ACTH stimulate blood flow; and how does increased blood (or perfusion medium) flow stimulate steroidogenesis? Addressing the first question, we have recently identified mast cells in the adrenal capsule, and shown that Compound 48/80, a mast cell degranulator, mimics the actions of ACTH on adrenal blood flow and corticosterone secretion. We have also demonstrated an inhibition of the adrenal vascular response to ACTH in the presence of disodium cromoglycate, which prevents mast cell degranulation. We conclude, therefore, that ACTH stimulates adrenal blood flow by its actions on mast cells in the adrenal capsule. Addressing the second question, we looked at the role of endothelin in the rat adrenal cortex. Endothelin 1, 2 and 3 caused significant stimulation of steroid secretion by collagenase dispersed cells from both the zona glomerulosa and the zona fasciculata. A sensitive response was seen, with significant stimulation at an endothelin concentration of 10(-13) mol/l or lower. Endothelin secretion by the in situ isolated perfused rat adrenal gland was measured using the Amersham assay kit. Administration of ACTH (300 fmol) caused an increase in the rate of immunoreactive endothelin secretion, from an average of 28.7 +/- 2.6 to 52.6 +/- 6 fmol/10 min (P less than 0.01, n = 5). An increase in immunoreactive endothelin secretion was also seen in response to histamine, an adrenal vasodilator, which stimulates corticosterone secretion in the intact gland, but has no effect on collagenase-dispersed cells. From these data we conclude that endothelin may mediate the effects of vasodilation on corticosterone secretion, and this mechanism may explain some of the differences in response characteristics between the intact gland and dispersed cells.
J Steroid Biochem Mol Biol 1991
PMID:The relationship between adrenal vascular events and steroid secretion: the role of mast cells and endothelin. 165 78

The metabolic pathways of medazepam, oxazepam, and diazepam were modeled using graph-theoretic transforms which are incorporable into computer-assisted metabolic analysis programs. The information, represented in the form of a graph-theoretic transform kit, which was obtained from these pathways was then used to predict the metabolites of other benzodiazepine compounds. The transform kits gave statistically significant predictions with respect to a statistical method for evaluating the performance of the transform kits.
J Comput Aided Mol Des 1991 Aug
PMID:A graph-theoretic approach to modeling metabolic pathways. 168 17

The c-kit proto-oncogene, the cellular homolog of the transforming gene of a feline retrovirus, encodes a transmembrane tyrosine kinase homologous to receptors for growth factors. To study the cellular function of c-kit, we constructed a chimeric molecule composed of the extracellular portion of the receptor for epidermal growth factor (EGF) and the transmembrane and cytoplasmic domains of p145kit. The hybrid molecule was properly expressed in murine fibroblasts and displayed specific binding of EGF (Kd, 3 x 10(-8) M). Activation of the chimeric receptor by EGF stimulated the tyrosine kinase activity of kit and led to the generation of a potent mitogenic signal. Moreover, cells expressing the chimeric receptor acquired a transformed phenotype once they were stimulated with the heterologous ligand.
Mol Cell Biol 1990 Nov
PMID:Receptor functions and ligand-dependent transforming potential of a chimeric kit proto-oncogene. 170 Feb 79

To facilitate the clinical application of dot-blot hybridization for assaying hepatitis B virus (HBV) DNA, we compared the ability of nucleic acid probes labelled with 32P or with various non-radioactive markers to detect HBV DNA in patient serum. Cloned HBV DNA was hybridized with (1) 32P-labelled HBV DNA cloned in M13, (2) the 32P-labelled HBV RNA probe included in the HepProbe kit, (3) an alkaline phosphatase-labelled synthetic oligonucleotide of HBV, (4) biotin-labelled HBV DNA, and (5) sulphonated HBV DNA. Detection was either by autoradiography or an enzymatic colour reaction. The lowest level of detection of cloned HBV DNA was achieved with the 32P-labelled HBV RNA probe (0.3 pg HBV DNA, corresponding to 3 x 10(4) genomes in 50 microliters), followed by the 32P-labelled DNA probe (0.3-2 pg), sulphonated DNA (1-2 pg), biotin-labelled DNA (4 pg), and an alkaline phosphatase-labelled synthetic oligonucleotide (30 pg). Subsequently, sera from 159 patients with various constellations of HBsAg, HBeAg, and anti-HBe were tested with the most sensitive radioactive method (HepProbe) and the corresponding nonradioactive method (sulphonation). The overall concordance rate was 71% (r = 0.42). Compared with HepProbe results, sulphonation showed a sensitivity of 80% and a specificity of 67%. We conclude that radiolabelling (in particular 32P-labelling of HBV RNA) still allows the most sensitive and reliable detection of HBV DNA in patient serum using conventional dot-blot hybridization.
Mol Cell Probes 1991 Aug
PMID:Detection of hepatitis B virus DNA in serum with nucleic acid probes labelled with 32P, biotin, alkaline phosphatase or sulphone. 179 50

Routinely, we detect 0,1 pg of plasmid DNA using the nonradioactive DNA labeling and detection kit produced by Boehringer Mannheim (FRG). Using the kit we have determined the carrier status of a woman in a family with a case of Duchenne muscular dystrophy by the blot hybridization technique.
Mol Gen Mikrobiol Virusol 1991 May
PMID:[Use of nonradioactively labelled DNA-probes for DNA-diagnosis of Duchenne's muscular dystrophy]. 189 56

From 1984 to 1990, human breast cancer estrogen receptors have been measured both by a radioligand assay (RLA[3H]estradiol) and by an enzyme immunoassay (Abbott ER-EIA kit). The ratio EIA/RLA results increased continuously from 1.04 (1984) to 1.87 (1990), and this evolution was consistent with the last trial of the E.O.R.T.C. receptor study group (Trial 1989-II, EIA/RLA = 2.5). Dilution studies of cytosols with the current ER-EIA kits showed an important parallelism defect of the standard curve, the final result of cytosols (fmol/mg protein) obtained from the upper part of the curve (between 100 and 500 fmol/ml) being 1.5 to 2 times higher than the results obtained from readings of the lower part of the standard curve (between 0 and 50 fmol/ml). Chromatographic experiments were carried out during 1986 and the measures of binding sites by RLA and of immunoreactive sites by EIA on chromatographic fractions were compared. Identical results were obtained with EIA and RLA, either on polymeric forms of the estrogen receptor, or on monomeric forms obtained after dissociation by 0.4 M KCl. The same experiments performed during 1990 showed that, in the chromatographic fractions, the concentration of immunoreactive sites was twice as large as that of ligand-binding sites, detected by tritiated estradiol. Furthermore, the detection of polymeric and monomeric receptor isoforms by monoclonal antibodies varied, and was increased by the presence of KCl (0.4 M) and/or bovine serum albumin (BSA) (1 mg/ml) in the cytosol. These findings showed that the large differences between enzyme immunoassay and ligand-binding assay results currently observed were due to differential reactivity of monoclonal antibodies for the estrogen receptor standard provided in the ER-EIA kits and for the estrogen receptor present in cytosols from human breast cancers, suggesting modifications of immunoreactivity of the monoclonal antibodies actually provided in the ER-EIA kits.
J Steroid Biochem Mol Biol 1991 Oct
PMID:Evolution of immunoreactivity of monoclonal antibodies H222 and/or D547 used in the detection of breast cancer estrogen receptors. Varying reactivity of receptor isoforms. 191 41

Previous studies from this laboratory have drawn attention to discrepancies between enzyme-linked immunoassay (EIA) and steroid binding assay (SBA) in the analysis of oestrogen receptors (ER) in breast tumours. In particular, EIA values were at least 3-fold higher than SBA values in tumours which also contained progesterone receptors (PR) when both 4 and 8S isoforms of the ER are present. To test the influence of these isoforms on the two assay systems, the relationships between the oestrogen receptor (ER) values obtained by EIA and SBA were examined in tumour cytosols prepared in the presence of molybdate and protease inhibitors to prevent degradation of the 8S form. Under these conditions, values for ER were the same by EIA and SBA (slope = 1.08, r = 0.886, n = 25) when EIA was performed using low salt phosphate buffer instead of the high salt-containing Abbott-diluent provided with the kit. However, after disruption of the 8S assembly using high K+ concentration, the slope of the regression was 6.37, r = 0.865, n = 25. Using ER from rat uterus, EIA was also performed on intact 8S oligomers, on 8S ER dissociated by high salt, and on glycerol density gradient-fractionated 4S ER. The identity of the ER oligomers and components was confirmed by glycerol density gradient fractionation, and by isoelectric focussing. For the 4S ER, EIA gave similar values whether using low or high salt phosphate buffer. However EIA values for the 8S form were 2-fold higher when the supplied diluent was used than when the assay was performed in low salt buffer. The amount of oestradiol which could be extracted was affected by the different conditions used. Addition of KCl or trypsin to disrupt the 8S ER caused an increase in the amount of extractable oestradiol compared with control values (control = 52 +/- 4.0, high KCl = 91 +/- 4.4, trypsin = 152 +/- 7.5, pg oestradiol/mg protein). We conclude that further antibody binding sites are revealed from the 8S ER form after its disaggregation by high salt. The steroid extraction data also suggests the possibility that tightly bound steroid is retained within the 8S ER structure, and released by 8S disaggregation. Both of these may contribute to the differences between EIA and SBA values.
J Steroid Biochem Mol Biol 1991 Nov
PMID:Significance of the 8S complex in oestrogen receptor recognition. 195 7


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