Search PubMed⌕ Search

Biomedical subjects

T Das

Publications and source records attributed to T Das.

At least 109 records · Page 6Linked to original sources
PubMed1995

Involvement of cellular casein kinase II in the phosphorylation of measles virus P protein: identification of phosphorylation sites.

The phosphoprotein P gene of measles virus (Edmonston strain) has been cloned in the Escherichia coli expression vector pET-3a with a histidine tag at the C-terminal end. The expressed protein was soluble, unphosphorylated, and constituted 10 to 20% of total cellular protein. Recombinant P protein purified by Ni-affinity chromatography was found to be efficiently phosphorylated in vitro by recombinant casein kinase II (CKII) or by the CKII activity present in the uninfected cell extract. A comparison of phosphopeptide analyses between the in vivo- and the in vitro-32P-labeled P proteins revealed that both proteins share common phosphorylation sites. In an attempt to identify the exact site of the CKII-mediated phosphorylation, we altered specific serine residues located within the CKII consensus motif to alanine by site-directed mutagenesis. The results indicate that Ser 86, Ser 151, and Ser 180 located within the N-terminal half of the P protein are involved in the CKII-mediated phosphorylation of the P protein.

Alkaloids↗
PubMed1995

Casein kinase II is the P protein phosphorylating cellular kinase associated with the ribonucleoprotein complex of purified vesicular stomatitis virus.

Protein kinase activities associated with a highly purified transcriptionally active ribonucleoprotein complex from the virions of vesicular stomatitis virus (VSV) were isolated and characterized. Based upon several biochemical and immunological criteria, the protein kinase activity, which phosphorylated the bacterially expressed unphosphorylated (Po) protein, was shown to be cellular casein kinase II (CKII). These studies included inhibition of the protein kinase by specific inhibitors, phosphorylation of mutant phosphoproteins (P), immunoprecipitation by CKII antibody and Western blot analyses, and finally its ability to activate Po to synthesize RNA in a transcription-reconstitution reaction. The P protein is phosphorylated intracellularly by cellular CKII. The present study demonstrates that VSV specifically packages CKII which remains strongly associated with the ribonucleoprotein complex during morphogenesis.

Amino Acid Sequence↗
PubMed1995

Postsurgical endophthalmitis: diagnosis and management.

Infectious endophthalmitis following intraocular surgery is a complication that could cause severe visual loss or loss of the eye. The categorisation of the event that led to intraocular infection will help the clinician to predict the infectious agent and begin appropriate therapy. Most of the cases of postsurgical endophthalmitis are seen following cataract surgery. It is important for all ophthalmologists, irrespective of specialisation and areas of interest, to be familiar with the management of endophthalmitis. This review briefly describes the facets of clinical and laboratory diagnosis, pathology, and management. While the different viewpoints in the management of endophthalmitis are mentioned in appropriate places, more attention is paid to present a rational approach to the management of endophthalmitis.

Anti-Bacterial Agents↗
PubMed1994

Gh: a GTP-binding protein with transglutaminase activity and receptor signaling function.

The alpha 1-adrenergic receptors activate a phospholipase C enzyme by coupling to members of the large molecular size (approximately 74 to 80 kilodaltons) G alpha h family of guanosine triphosphate (GTP)-binding proteins. Rat liver G alpha h is now shown to be a tissue transglutaminase type II (TGase II). The transglutaminase activity of rat liver TGase II expressed in COS-1 cells was inhibited by the nonhydrolyzable GTP analog guanosine 5'-O-(3-thiotriphosphate) or by alpha 1-adrenergic receptor activation. Rat liver TGase II also mediated alpha 1-adrenergic receptor stimulation of phospholipase C activity. Thus, G alpha h represents a new class of GTP-binding proteins that participate in receptor signaling and may be a component of a complex regulatory network in which receptor-stimulated GTP binding switches the function of G alpha h from transglutamination to receptor signaling.

Amino Acid Sequence↗
PubMed1994

Effect of fatty acid binding proteins on developing human placental malate dehydrogenase activity.

Role of fatty acid binding proteins (FABPs) in modulating inhibition of human placental malate dehydrogenase by palmitoyl-CoA and oleate has been studied. Activity of human placental cytosolic malate dehydrogenase is detected throughout the gestation, showing a peak at midgestation (20-25 weeks). Inhibition (50%) of the enzyme activity is obtained by 20 microM palmitoyl-CoA or 35 microM oleate. FABPs enhance the activity of malate dehydrogenase in absence of palmitoyl-CoA or oleate and also protect against palmitoyl-CoA or oleate inhibition. Such a modulatory effect of FABP may be due to the binding of long chain fatty acyl-CoA or fatty acid rather than a direct effect of FABPs on the enzyme.

Carrier Proteins↗
PubMed1994

Selection of surgical technique for retinal detachment with coloboma of the choroid.

Four eyes with rhegmatogenous retinal detachment and coloboma of the choroid were managed by conventional scleral buckling (one eye); scleral buckling combined with lensectomy, vitrectomy, and fluid-air exchange (two eyes); and vitrectomy, silicone oil injection without scleral buckling (one eye). Retinal break was seen within the coloboma in two eyes, at the periphery in one eye, and, both in the coloboma and periphery in one eye. At a follow-up of 15 months, the retina was found attached in all the patients. The success of these surgical procedures could be attributed to careful preoperative/intraoperative fundus examination and individualised surgical planning.

Adult↗
PubMed1994

Eales' disease.

Explore the source record for details and available documents.

Humans↗
PubMed1993

Evidence that the Gh protein is a signal mediator from alpha 1-adrenoceptor to a phospholipase C. I. Identification of alpha 1-adrenoceptor-coupled Gh family and purification of Gh7 from bovine heart.

Our previous studies on alpha 1-adrenoceptor-mediated signaling suggested that Gh is a signal mediator. Gh consists of a 74-kDa GTP-binding alpha-subunit and a 50-kDa beta-subunit. Studies using the alpha 1-agonist-receptor-G-protein ternary complexes from various tissues and species revealed that the intensity (GTP-binding) of the [alpha-32P]GTP-labeled proteins resulting from activating the alpha 1-receptor was significantly attenuated by phentolamine. The molecular masses of GTP-binding proteins were 74 kDa in rat heart and liver, 77 kDa in dog heart, 78 kDa (Gh7 alpha) in bovine heart and liver, and 80 kDa in human heart. Supporting these observations, a specific antibody to Gh7 alpha not only recognized these GTP-binding proteins in the ternary complex preparations, but also co-immunoprecipitated alpha 1-adrenoceptors, indicating a tight association of these GTP-binding proteins with the alpha 1-adrenoceptor. These results also demonstrate that functional and structural similarities exist among these GTP-binding proteins. Additionally, one of the identified G-proteins (termed Gh7) was purified from bovine heart. Gh7 consisted of the 78-kDa GTP-binding protein and a 50-kDa protein.

Animals↗
PubMed1993

Evidence that the Gh protein is a signal mediator from alpha 1-adrenoceptor to a phospholipase C. II. Purification and characterization of a Gh-coupled 69-kDa phospholipase C and reconstitution of alpha 1-adrenoceptor, Gh family, and phospholipase C.

Our studies on the alpha 1-adrenoceptor signaling have demonstrated that the Gh family is a signal mediator. We report here that a 69-kDa phospholipase C (PLC) is the effector in this signal pathway. The enzyme was isolated by dissociating a Gh7-PLC complex which was induced in the bovine liver membranes incubating with (-)-epinephrine and GTP. The enzyme displayed a marked preference hydrolysis for phosphatidylinositol 4,5-bisphosphate over other phosphatidylinositides at micromolar calcium. Reconstitution of PLC with the alpha 1-adrenoceptor and Gh (Gh7) into phospholipid vesicles resulted in a lowered Ca2+ requirement for the substrate hydrolysis in the presence of guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) when the receptor was activated with the alpha 1-agonist. The formation of inositol phosphate was hormone concentration dependent and reached maximal within 3 min which was faster than the formation in the presence of the alpha 1-antagonist. An Gh7 alpha antibody co-immunoprecipitated 80-85% of phospholipase C activity in the presence of GTP gamma S, but not in the presence of GDP or buffer, showing the association of PLC with the alpha-subunit of Gh family. Thus, our novel approaches to identify the effector involved in the alpha 1-adrenoceptor signaling, as well as the reconstitution studies, substantially demonstrate that the alpha 1-adrenoceptor-mediated transmembrane signaling involves the Gh family and a 69-kDa PLC.

Animals↗
PubMed1993

Characterization and binding properties of human fetal lung fatty acid-binding proteins.

When delipidated Mr > 10,000 cut-off human fetal lung cytosol was separated on gel filtration and ion-exchange chromatography on Auto-FPLC system, two fatty acid-binding proteins (FABPs) of pI 6.9 and pI 5.4 were purified to homogeneity. On Western blotting analysis with the anti-human fetal lung pI 6.9 FABP, these two proteins showed immunochemical cross reactivity with each other and with purified hepatic FABPs but not with cardiac or gut FABP. These two FABPs have identical molecular mass of 15.2 kDa, which is slightly higher than that of the hepatic proteins (14.2 kDa). Carbohydrate covalently linked to FABPs, that may substantially add to the molecular mass, was not detected in the purified protein preparations. Amino acid analysis revealed that both the proteins have same amino acid composition each containing one Trp residue that is lacking in hepatic FABP. Different isoforms of lung FABP exhibited different binding ability for their natural ligands. These proteins bind palmitoyl CoA with higher affinity than oleic acid. pI 6.9 FABP can more rapidly and efficiently transfer fatty acid than can pI 5.4 FABP from unilammelar liposomes. Thus these FABPs may play a critical role in fatty acid transport during human fetal lung development.

Acyl Coenzyme A↗
PubMed1993

Mapping of interacting domains between the nucleocapsid protein and the phosphoprotein of vesicular stomatitis virus by using a two-hybrid system.

Specific interaction between the nucleocapsid protein (N) and the phosphoprotein (P) of vesicular stomatitis virus (VSV), an important step in the life-cycle of the virus, was studied by using a two-hybrid system. Plasmids encoding P fused with the yeast GAL4 DNA-binding domain (pGALP) and N fused with the herpes simplex virus VP16 transactivating region (pVPN) were transfected into CHO cells along with a reporter plasmid encoding chloramphenicol acetyltransferase (CAT). The ability of N and P to associate in vivo was measured by activation of the CAT gene by the VP16 transactivating region. Transfection of plasmids pGALP and pVPN resulted in a high level of CAT activity, indicating that the N and P portions of the fusion proteins associated very strongly with each other. Progressive C-terminal deletions of the P protein revealed two regions that are important for association with the N protein: the N-terminal acidic domain and the C-terminal basic domain. Phosphorylation of P protein was not required for N-P association. Various deletions and mutations of the N protein revealed the C-terminal 5 amino acids (Val-Glu-Phe-Asp-Lys), in particular the amino acids Val-Glu-Phe, to be critical for N association with P. This two-hybrid system can be used in other viral systems to study the interaction between proteins involved in transcription and replication.

Amino Acid Sequence↗
PubMed1993

Characterization of cardiac fatty-acid-binding protein from human placenta. Comparison with placenta hepatic types.

When a 105,000 x g supernatant of human placenta was incubated with [1-14C]oleate and subjected to Sephadex G-75 gel filtration and HPLC, two fatty-acid-binding protein (FABP) peaks were obtained. One of these, when further purified by carboxymethyl-cellulose, gave one 15.3-kDa FABP with pI5.3. The other, when chromatographed on DEAE cellulose, separated into two 14.2-kDa FABP with pI6.9 and 5.4. Purity of the proteins was checked by SDS/PAGE. Molecular mass, pI, immunochemical properties and amino acid compositions all indicated that 15.3-kDa FABP was of the cardiac type, whereas both 14.2-kDa FABP were of the hepatic type. Cardiac FABP did not cross-react with hepatic proteins. When tested for the acceptor/donor properties of these FABP, hepatic types were found to be better candidates than cardiac in uptaking fatty acids from liposomes. Cardiac FABP, on the other hand, acted in a more efficient way as a donor, indicating a distinct role of these proteins in human placenta, which furnishes a multiorgan system for the developing fetus.

Amino Acids↗
PubMed1993

Modification of clastogenicity of three known clastogens by garlic extract in mice in vivo.

The anticlastogenic activity of crude extract of garlic (Allium sativum L.) was studied in bone marrow cells of mice. Male laboratory-bred Swiss albino mice were given one of three concentrations of the freshly prepared extract (100 mg, 50 mg, and 25 mg/kg body weight) as a dietary supplement by gavage for 6 consecutive days. On the seventh day the mice were administered a single acute dose of two known clastogens, mitomycin C(1.5 mg/kg) and cyclophosphamide (25 mg/kg) or sodium arsenite (2.5 mg/kg), simultaneously with garlic extract. After 24 hr, chromosome preparations were made from the bone marrow cells. The endpoint studied were chromosomal aberrations and damaged cells. Garlic extract alone induced a low level of chromosomal damage. The clastogenicity of all three mutagens were reduced significantly in the animals which had been given garlic extract as dietary supplement. The extent of reduction was different for the three clastogens and may be attributed to the interaction with the different components of the extract.

Analysis of Variance↗
PubMed1993

Expression of the vesicular stomatitis virus nucleocapsid protein gene in Escherichia coli: analysis of its biological activity in vitro.

The nucleocapsid (N) protein genes of vesicular stomatitis virus, serotypes New Jersey and Indiana, were expressed in Escherichia coli BL21(DE3) transformed by the recombinant expression vector pET-3a containing N genes under the control of the T7 RNA polymerase promoter. Following induction with isopropylthiogalactopyranoside, the N protein was synthesized, representing 10 to 20% of total cellular protein. The N protein remained in a nonaggregated form in 1 M NaCl solution. The purified N protein was found to be biologically active as demonstrated by its encapsidation of preformed leader RNA as well as its synthesis of genome length RNA in an in vitro transcription-replication reaction. The availability of recombinant N protein in a sufficient amount would facilitate structure and function studies of this important viral protein.

Base Sequence↗
PubMed1993

Acidic domain of the phosphoprotein (P) of vesicular stomatitis virus differentially interacts with homologous and heterologous nucleocapsid protein (N).

The homologous and heterologous interactions between the nucleocapsid protein N and the phosphoprotein P of New Jersey and Indiana serotypes of vesicular stomatitis virus were studied. SP6 derived N and P mRNAs were cotranslated in rabbit reticulocyte lysate and the complexes formed thereof were analyzed by 7.5% nondenaturing polyacrylamide gel electrophoresis. P protein of VSV(NJ) has two binding sites for homologous N protein: One located within the C-terminal 11 amino acids (within domain III) is responsible for the formation of five specific complexes while the other site, which spans the acidic domain I, is necessary for the formation of the sixth complex only. In contrast, P(IND) does not form the sixth complex when interacted with homologous N protein. Interestingly, P(NJ) forms only complexes 1 to 5 when it interacts with N(IND). The above results suggest that the complex 6 formation or domain I interacting site is NJ-serotype specific. Two chimeric P proteins were made using heterologous domains I and II/III of the P proteins of both serotypes. The soluble interaction of the chimeric proteins with the N protein supported the observed serotype specific interactions. The chimeric P proteins bound with equal efficiency with N-RNA template of both serotypes. These results strongly suggest that the acidic domain I of the P protein differentially interacts with homologous and heterologous N proteins. The biological significance of these findings is discussed.

Animals↗