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

Kinetics of incorporation of (3H) uridine into cytoplasmic RNA fractions of rat liver is investigated. The fractions include free and membrane bound polysomes, rough membranes sedimenting with mitochondria and free cytoplasmic RNA particles. (1) Poly(A) containing RNA, isolated by oligo-dT cellulose, amounts to 0.4% of the total RNA in the homogenate, 0.5% in bound polysomes, 3.4% in free polysomes and 16% in free cytoplasmic RNA particles. (2) The rate of (3H) uridine incorporation into RNA lacking poly(A) proceeds uniformly in all subcellular fractions except for free cytoplasmic RNA particles, which accumulate negligible amounts of radioactivity. (3) The initial labelling of RNA containing poly(A) is most active in free cytoplasmic RNA particles supporting their identity as mRNA en route to polysomes. The initial specific radioactivities decrease in the following order: homogenate, bound polysomes, rough membranes sedimenting with mitochondria, free polysomes. The data suggest that mRNA is supplied to free and membrane-bound polysomes via different routes. The kinetic analysis indicates that free cytoplasmic RNA particles may be a precursor of mRNA of free polysomes rather than that of bound polysomes. (4) The kinetic differences of free and membrane bound polysomes are also demonstrated by comparing the radioactivity of RNA containing poly(A) to the total radioactivity at various incorporation times. In bound polysomes this decreases from 31% at 1 h to 10% at 25 h, whereas in free polysomes the corresponding ratio increases from 10 to 13%. RNA containing poly(A) of free cytoplasmic RNA particles represents 64% of the total radioactivity throughout the experiment.
Mol Cell Biochem 1975 Aug 30
PMID:Labelling kinetics of RNA containg poly(A) in liver subcellular fractions. 116 64

Administration of hydrocortisone to adrenalectomised rats elevated levels of both free and membrane-bound polysomes in liver and led to marked shifts in their sedimentation profiles in favour of heavier polysomes. The rate of nascent polypeptide formation was also found to be enhanced in response to the hormone but this effect was mainly confined to the site of free polysomes. These results suggest that besides its well-known potentiating action at the transcription level, the hormone elicits selective stimulatory response at the translation level.
Mol Cell Endocrinol 1976 Feb
PMID:Action of hydrocortisone at a translational level in the rat liver. 124 70

A three-step sequential detergent/salt extraction procedure was used in order to isolate three distinct subcellular fractions containing free (FP), cytoskeletal-bound (CBP) and membrane-bound polysomes (MBP), respectively, from Krebs II ascites cells (Vedeler et al., Mol Cell Biochem 100: 183-193, 1991). The purpose was to study changes in the distribution of polysomes in these three fractions during long-term incubation with insulin under either stationary conditions or in roller suspension culture. Insulin caused a redistribution of polysomes between FP, CBP and MBP fractions. The hormone appeared to promote an entry of ribosomes into polysomes both in CBP and MBP populations. When cells were grown in stationary culture in the presence of insulin and thus promoted to attach to the substratum and undergo morphological changes, a diversion of ribosomes from CBP into MBP was observed. The level of protein synthesis was apparently very high in this latter fraction since more than 70% of ribosomes were in polysomes. Morphological changes observed following insulin treatment were accompanied by a shift of certain proteins among subcellular fractions (for example actin and p35). The fibronectin content was about 20% higher in attached compared to non-attached cells. The results suggest that morphological changes induced by stimulation with insulin are associated with an increased activity of MBP, presumably reflecting a requirement for an increased synthesis of membrane proteins.
Mol Cell Biochem 1992 Dec 16
PMID:Morphological changes in Krebs II ascites tumour cells induced by insulin are associated with differences in protein composition and altered amounts of free, cytoskeletal-bound and membrane-bound polysomes. 129 8

Rat ovarian membrane luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptor was reconstituted into proteoliposomes. The ability of sodium cholate to extract and reconstitute hCG binding activity was dependent on the protein/detergent ratio. Trypsinization of the LH/hCG receptor containing proteoliposomes indicated that approximately 57% of hCG binding sites were oriented extravesicularly. The presence of 20% glycerol or other osmolytes during reconstitution increased the accessibility of LH/hCG receptors but not the activity of adenylate cyclase in proteoliposomes. This beneficial effect was independent of any specific detergent or its presence during detergent solubilization of proteins. Dynamic properties of membranes were monitored by electron spin resonance of 16-, 12-, and 5-doxyl stearic acid. Reconstituted proteoliposomes contain less ordered membrane lipids than do native membranes. Addition of glycerol before reconstitution increased the order of lipid bilayer and shifted it to the physical state of the native membrane. These findings are consistent with the hypothesis that a rise in membrane ordering increases the accessibility of membrane-bound LH/hCG receptors.
Mol Cell Endocrinol 1992 Feb
PMID:Osmolytes improve the reconstitution of luteinizing hormone/human chorionic gonadotropin receptors into proteoliposomes. 131 90

Five rat thyroid cell lines were tested for the expression of the cell surface receptor for urokinase type plasminogen activator (uPA). All tested lines were found to bind uPA, but transformed 1-5G and Ki-Mol cells, which are also high uPA producers, bound at least ten times more uPA, as compared to non-producers, 'normal' TL5 cells. Moreover, it was possible to remove membrane-bound uPA by treating the cells with phosphatidylinositol-specific phospholipase C, suggesting that rat uPAR, like its human counterpart, is linked to the membrane by a glucosyl-phosphatidylinositol anchor. The specificity of the binding was tested by competition with three different synthetic peptides corresponding to amino acids 14-37 of human, rat and mouse uPA. The results indicate also that the receptor binding region of rat uPA is located within the growth factor domain of the molecule and that its expression may be dependent on the transformed state of the cells.
 ...
PMID:The receptor for the plasminogen activator of urokinase type is up-regulated in transformed rat thyroid cells. 132 34

Using a powerful expression cloning method in COS cells, we have cloned the TGF-beta types II and III receptors. The type III TGF-beta receptor is a membrane-bound proteoglycan with a core protein of about 110 kDa. Stable expression of the type III receptor in L6 myoblasts leads to an apparent increase in the ability of the type II receptor to bind iodinated TGF-beta 1. The cloned type II receptor has a predicted protein core of about 60 kDa with a cysteine-rich extracellular domain, a single transmembrane domain, and a functional serine/threonine kinase domain that is homologous to the activin receptor and to the C. elegans protein daf-1. These results implicate serine/threonine phosphorylation as an important mechanism of TGF-beta action.
Mol Reprod Dev 1992 Jun
PMID:Expression cloning of TGF-beta receptors. 132 47

The intracellular mechanisms of action of alpha-MSH in rat adrenocortical cells were examined. When rat adrenal capsule (largely glomerulosa) cells were stimulated with a range of concentrations of alpha-MSH there was significant stimulation of aldosterone secretion at 10(-10) mol/l, although cyclic AMP was not increased until high concentrations of alpha-MSH were used (10(-6) mol/l and above). However, cells incubated with ACTH showed an increase in aldosterone secretion at 10(-11) mol/l and levels of cyclic AMP were elevated at 10(-9) mol ACTH/l. When rat adrenal whole capsules were incubated with alpha-MSH, membrane-bound protein kinase C (PKC) activity was increased and cytosolic enzyme activity decreased, showing PKC activation. Stimulation with angiotensin II also induced translocation of PKC activity, but ACTH did not. When [3H]inositol-loaded glomerulosa cells were stimulated with alpha-MSH there was significant generation of [3H]inositol trisphosphate (IP3) at concentrations of alpha-MSH which stimulated secretion of aldosterone. Significantly increased levels of [3H]IP3 were also measured when loaded cells were exposed to angiotensin II. ACTH did not cause any significant stimulation of [3H]IP3 production at any concentration used. These results indicate that activation of PKC and phospholipase C is important in modulating the steroidogenic effect of alpha-MSH.
J Mol Endocrinol 1992 Aug
PMID:Studies on the intracellular mechanism of action of alpha-melanocyte-stimulating hormone on rat adrenal zona glomerulosa. 132 51

The Src-like protein-tyrosine kinases Fyn and Lyn are expressed in lymphocytes. Fyn is expressed in T cells at elevated levels and is associated with the T cell antigen receptor complex, whereas Lyn is expressed in B cells and is associated with membrane-bound immunoglobulin. Thus, these kinases are suggested to participate in antigen-mediated signal transduction in lymphocytes. Previous report showed that fyn was also expressed in brain, but its cellular distribution was not examined. Expression of Lyn in neural tissues was not previously reported. Here we report that both fyn and lyn are expressed in discrete regions of the brain. To throw light on their functions in the brain, we investigated their expressions during brain ontogenesis in mice. In situ hybridization analysis showed that Fyn mRNA was specifically expressed in neurons of embryos and newborn mice. In adult animals, fyn mRNA was expressed in oligodendrocytes as well as neurons. In contrast, the expression of lyn mRNA was relatively low in brains of embryos and newborn mice, but in adults the transcript was specifically expressed in the granular layer of the cerebellum. Therefore, the Fyn and Lyn kinases may regulate distinct functions of specific cells during brain development. The specific expressions of Fyn and Lyn in both lymphatic and neural tissues could suggest common signalling mechanisms in the immune system and central nervous system.
Brain Res Mol Brain Res 1992 Dec
PMID:Specific expressions of Fyn and Lyn, lymphocyte antigen receptor-associated tyrosine kinases, in the central nervous system. 133 39

In order to identify potential markers of malignancy in diagnostic respiratory cytopathology, c-myc and c-erbB-2 proto-oncogene expression was studied in fine needle aspirates from 14 consecutive fresh operation tissue samples (after surgical removal) representing lung tumors and a variety of other cell samples by in situ hybridization of 35S-labeled antisense and sense RNA c-myc and c-erbB-2 specific proto-oncogene probes. All 14 lung tumors showed c-myc expression and eight also showed c-erbB-2 expression. On average, the c-myc expression was about 4 times higher than that of c-erbB-2 (P less than 0.001). c-erbB-2 expression, confirmed also as a cytoplasmic membrane-bound reactivity by immunohistochemical stainings for c-erbB-2 oncoprotein, was significantly related to adenocarcinoma (P less than 0.025), whereas increasing tumor size correlated significantly with increasing c-myc expression (P less than 0.05). On average, all the tumor cell lines showed 2-fold expression of c-myc compared with the lung tumors (P less than 0.025). c-erbB-2 expression was found in six of 11 cell lines. High c-myc proto-oncogene expression was also found in broncho-epithelial cells and alveolar macrophages, and a low expression was found in lymphocytes but not in neutrophils, while none of these cells showed c-erbB-2 proto-oncogene expression. Our results demonstrate extensive c-myc proto-oncogene expression in both malignant and non-neoplastic proliferating cells, but not in terminally differentiated cells such as neutrophils. Therefore c-myc expression must also be related to general cell proliferation and not only malignancy per se. In marked contrast, c-erbB-2 proto-oncogene expression was found only in adenocarcinoma cells, and thus can be used as a marker for malignancy in diagnostic respiratory cytopathology.
Am J Respir Cell Mol Biol 1992 Sep
PMID:Evidence by in situ hybridization that c-erbB-2 proto-oncogene expression is a marker of malignancy and is expressed in lung adenocarcinomas. 135 55

The brain cyclic AMP generation was studied in rats subjected to 15 min of cardiac arrest. We have used a particulate, synaptoneurosomal fraction to demonstrate the effect of ischemia in vivo on the responsiveness of adenylate cyclase (AC) system. It has been shown that, although there is a slight decrease in AC activity after ischemia, the in vitro fractions produce more cAMP in response to a variety of stimuli, suggesting an indirect, nonadenylate cyclase activation mechanism. For elucidation of this mechanism we have probed phorbol-12,13-dibutyrate (PDBu) as a direct PKC activator, forskolin to activate the catalytic subunit of AC, and cholera toxin (CT) for stabilizing the active, GTP-bound form of stimulatory guanine nucleotide binding protein (Gs). All these postreceptor AC modulators as well as the receptor activators such as adenosine and alpha 1-adrenergic agonists markedly enhanced cAMP production in the rat brain particulate fraction, although the postischemic hyperactive response to these stimuli was still present. However, when AC was stimulated by the combination of CT and PDBu, cAMP responses were identical in both control and postischemic fractions. The data, taken together, support the hypothesis that ischemia increases cAMP accumulation by facilitating the postreceptor AC activation through a PKC-involving pathway and by promoting the stronger coupling of membrane AC receptors with G-protein. Protein kinase C (PKC) activity during cerebral ischemia was also investigated. In contradistinction to our expectation PKC decreased significantly in the ischemic brain to 85% of the control activity in the cytosol and 72% in the membranes. However, in the incubated post-ischemic brain particulate fraction a relative increase in the membrane-bound form of the enzyme, from 30% for control to 53% for ischemia, was observed. This may suggest that ischemia-induced membrane changes could promote the enzyme translocation/activation during recovery, resulting in the sensitization of cAMP producing system.
Mol Chem Neuropathol 1992 Aug
PMID:Postreceptor modulation of cAMP accumulation in rat brain particulate fraction after ischemia--involvement of protein kinase C. 135 40


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>