Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The basis for impaired reduced folate carrier (RFC) activity in methotrexate-resistant CCRF-CEM (CEM/Mtx-1) cells was examined. Parental and CEM/Mtx-1 cells expressed identical levels of the 3. 1-kilobase RFC transcript. A approximately 85-kDa RFC protein was detected in parental cells by photoaffinity labeling and on Western blots with RFC-specific antiserum. In CEM/Mtx-1 cells, RFC protein was undetectable. By reverse transcriptase-polymerase chain reaction and sequence analysis, G to A point mutations were identified in CEM/Mtx-1 transcripts at positions 130 (P1; changes glycine 44 --> arginine) and 380 (P2; changes serine 127 --> asparagine). A 4-base pair (CATG) insertion detected at position 191 (in 19-30% of cDNA clones) resulted in a frameshift and early translation termination. Wild-type RFC was also detected (0-9% of clones). Wild-type RFC and double-mutated RFC (RFCP1+P2) cDNAs were transfected into transport-impaired K562 and Chinese hamster ovary cells. Although RFC transcripts paralleled wild-type protein, for the RFCP1+P2 transfectants, disproportionately low RFCP1+P2 protein was detected. This reflected an increased turnover of RFCP1+P2 over wild-type RFC. RFCP1+P2 did not restore methotrexate transport; however, uptake was partially restored by constructs with single mutations at the P1 or P2 loci. Cumulatively, our results show that loss of transport function in CEM/Mtx-1 cells results from complete loss of RFC protein due to early translation termination and increased turnover of a mutant RFC protein.
...
PMID:Impaired membrane transport in methotrexate-resistant CCRF-CEM cells involves early translation termination and increased turnover of a mutant reduced folate carrier. 1018 28

We cloned and sequenced a mouse gene encoding a new type of membrane bound serine protease (epithin) containing a multidomain structure. The initial cDNA clone was found previously in a polymerase chain reaction (PCR)-based subtractive library generated from fetal thymic stromal cells, and the message was shown to be highly expressed in a thymic epithelial nurse cell line. A clone isolated from a severe combined immunodeficiency (SCID) thymus library and extended to its full length at the 5' end with the RACE technique contains an open reading frame of 902 amino acids. Based on the sequence of this clone, the predicted protein structure is a type II membrane protein with a C-terminal serine protease domain linked to the membrane by four low density lipoprotein receptor modules and two CUB domains. High message expression by northern blotting was detected in intestine, kidney, lung, SCID, and Rag-2(-/-) thymus, and 2-deoxyguanosine-treated fetal thymic rudiment, but not in skeletal muscle, liver, heart, testis, and brain. Sorted MHC class II+ and II- fetal thymic stromal cells were positive for expression by reverse transcriptase-PCR, whereas CD45(+) thymocytes were not. The gene was found in chicken and multiple mammalian species under low stringency Southern hybridization conditions. Under high stringency conditions, only a single gene per haploid genome was identified in the mouse. This gene, Prss14 (protease, serine, 14), was mapped to mouse chromosome 9 and is closely linked to the Fli1 (Friend leukemia integration 1) gene.
...
PMID:Cloning and chromosomal mapping of a gene isolated from thymic stromal cells encoding a new mouse type II membrane serine protease, epithin, containing four LDL receptor modules and two CUB domains. 1019 18

The avascular cornea has limited access to plasma proteins, including plasminogen, a protein that is synthesized by the liver and supplied to most tissues via the blood. Recent experiments by others using plasminogen-deficient mice revealed the importance of plasmin, the active form of plasminogen, for the maintenance of the normal cornea and for corneal wound healing [Kao, Kao, Bugge, Kaufman, Kombrinck, Converse, Good and Degan (1998) Invest. Ophthalmol. Vis. Sci. 39, 502-508; Drew, Kaufman, Kombrinck, Danton, Daugherty, Degen and Bugge (1998) Blood 91, 1616-1624]. In the present experiments, plasmin was identified as a major serine proteinase in the human cornea. The major plasminogen and plasmin forms on non-reducing zymograms and Western blots had Mr values of 76x10(3) and 85x10(3), with minor forms of Mr 200x10(3), 135x10(3), 68x10(3) and 45x10(3). Angiostatin-like peptides with Mrs of 48x10(3), 45x10(3) and 38x10(3) were observed which bound to lysine-Sepharose and reacted with anti-plasminogen monoclonal antibodies directed towards kringle domains 1-3 of plasminogen. The cornea contained 1.1+/-0.15 microgram of plasminogen+plasmin/cornea, or 0.54+/-0.05 microgram of plasminogen+plasmin/mg of protein. Cornea conditioned medium contained nine times the amount of plasminogen+plasmin that could be extracted from the cornea. These data suggested that corneal cells, unlike most extrahepatic cells, synthesize plasminogen. The synthesis of plasminogen by the cornea was confirmed by immunoprecipitation of metabolically labelled plasminogen, sequencing of its cDNA obtained by reverse transcriptase-PCR and inhibition of protein synthesis. Interleukins-1alpha and -1beta stimulated corneal plasminogen synthesis 2-3-fold; however, interleukin-6 decreased corneal plasminogen synthesis by approx. 40% at early times after addition of the cytokine. By 24 h of culture, no differences were noted in the presence and absence of interleukin-6. Thus the cornea can synthesize plasminogen and regulate its synthesis in response to its environment, including cytokines induced in the cornea by injury and inflammation. Therefore the cornea can control the amount of plasminogen, the precursor of both plasmin and angiostatin.
...
PMID:Extrahepatic synthesis of plasminogen in the human cornea is up-regulated by interleukins-1alpha and -1beta. 1021 10

Members of the protein kinase C (PKC) family of serine/threonine kinases are thought to play critical roles in the regulation of cellular differentiation and proliferation in many cell types. An additional member of the PKC family was identified through human expressed sequence tag (EST) database search and its full length cDNA was isolated. Sequence analysis revealed that the predicted translation product was composed of 890 amino acid residues and that the protein has 77.3% similarity to human PKC mu (PKCmu) and 77. 4% similarity to mouse PKD (the mouse homolog of PKCmu). We designated the new member as protein kinase C nu (PKCnu). The PKCnu messenger RNA was ubiquitously expressed in various tissues when analyzed by Northern blots and reverse transcriptase-coupled polymerase chain reaction (PCR) analyses. The chromosomal location of the gene was determined between markers WI-9798 and D2S177 on chromosome 2p21 region by PCR-based methods with both a human/rodent monochromosomal hybrid cell panel and a radiation hybrid mapping panel.
...
PMID:PKCnu, a new member of the protein kinase C family, composes a fourth subfamily with PKCmu. 1023 60

The performance of a silica chip-based resequencing method, the Affymetrix HIV PRT 440 assay (hereafter referred to as the Affymetrix assay), was evaluated on a panel of well-characterized nonclade B viral isolates and on isolates exhibiting length polymorphisms. Sequencing of human immunodeficiency virus type 1 (HIV-1) pol cDNAs from clades A, C, D, E, and F resulted in clade-specific regions of base-calling ambiguities in regions not known to be associated with resistance polymorphisms, as well as a small number of spurious resistance polymorphisms. The Affymetrix assay failed to detect the presence of additional serine codons distal to reverse transcriptase (RT) codon 68 that are associated with multinucleoside RT inhibitor resistance. The increasing prevalence of non-clade B HIV-1 strains in the United States and Europe and the identification of clinically relevant pol gene length polymorphisms will impact the generalizability of the Affymetrix assay, emphasizing the need to accommodate this expanding pool of pol genotypes in future assay versions.
...
PMID:Performance of the Affymetrix GeneChip HIV PRT 440 platform for antiretroviral drug resistance genotyping of human immunodeficiency virus type 1 clades and viral isolates with length polymorphisms. 1040 96

Molecular cloning of mouse decay accelerating factor (DAF; CD55) predicted two forms of the molecule, one transmembrane (TM) and the other glycosylphosphatidylinositol (GPI)-anchored; these are encoded by separate genes termed Daf-GPI and Daf-TM. In the present study several additional isoforms of mouse DAF, generated by alternative splicing from these genes, are described. Northern-blot analysis of RNA and reverse transcriptase-PCR from various tissues indicated that spleen and testis expressed high levels of DAF, which comprised several species. These species were cloned and sequence analysis revealed various novel forms in addition to those previously reported. Two novel forms were derived from the Daf-TM gene but the transmembrane sequence defined previously was replaced by a unique GPI-anchor addition sequence; one clone also had part of the serine/threonine/proline (STP) region deleted. A third clone, encoding a transmembrane protein, was also derived from this gene but the entire STP region was deleted. A fourth clone, derived from the Daf-GPI gene, contained a novel C-terminal sequence, suggestive of a secreted form of the protein. Two DAF cDNAs (TM and GPI-anchored) were stably expressed in Chinese hamster ovary cells. When these cells were attacked with mouse or rat complement and analysed for C3b deposition, DAF-transfected cells had greatly reduced C3b deposition compared with controls. Transfection with DAF also conferred protection from complement in a cell-lysis assay, and a soluble, recombinant form of mouse DAF inhibited complement in a haemolytic assay.
...
PMID:Molecular and functional analysis of mouse decay accelerating factor (CD55). 1041 49

Type 2C protein phosphatases (PP2Cs), a class of ubiquitous and evolutionally conserved serine/threonine protein phosphatases, are encoded in at least four distinct genes and implicated in the regulation of various cellular functions. Of these four PP2C genes, the expression of the PP2Cbeta gene has been reported to be tissue-specific and development-dependent. To understand more precisely the regulatory mechanism of this expression, we have isolated and characterized overlapping mouse genomic lambda clones. A comparison of genomic sequences with PP2Cbeta cDNA sequences provided information on the structure and localization of intron/exon boundaries and indicated that PP2Cbeta isoforms with different 5' termini were generated by alternative splicing of its pre-mRNA. The 5'-flanking region of exon 1 had features characteristic of a housekeeping gene: it was GC-rich, lacked TATA boxes and CAAT boxes in the standard positions, and contained potential binding sites for the transcription factor SP1. In the 5'-flanking region of exon 2, several consensus sequences were found, such as a TATA-like sequence and negative regulatory element box-1, -2 and -3. Subsequent analysis by transient transfection assay with a reporter gene showed that these regions act as distinct promoters. Analysis of PP2Cbeta transcripts by reverse transcriptase-PCR showed that exon-1 transcripts were expressed ubiquitously in all of the tissues examined, whereas exon-2 transcripts were predominantly expressed in the testis, intestine and liver. These results suggest that the alternative usage of two promoters within the PP2Cbeta gene regulates tissue-specific expression of PP2Cbeta mRNA.
...
PMID:Alternative promoters direct tissue-specific expression of the mouse protein phosphatase 2Cbeta gene. 1046 37

Human stratum corneum chymotryptic enzyme (SCCE) may play a central part in epidermal homeostasis. Its proposed function is to catalyze the degradation of intercellular structures, including desmosomes, in the stratum corneum as part of the desquamation process. In order to facilitate physiologic and pathophysiologic studies on SCCE we have looked for the corresponding murine enzyme. A cDNA obtained by reverse transcription-polymerase chain reaction with total RNA prepared from mouse tails as starting material was cloned, and the expression of the corresponding mRNA studied. The murine cDNA showed 77% homology to human SCCE cDNA. It had an open-reading frame encoding a protein comprising 249 amino acids with 82% amino acid sequence homology to human SCCE including the conserved sequences of the catalytic traid of mammalian serine proteases. The murine protein was deduced to have a 21 amino acid signal peptide and a four amino acid propeptide ending with a tryptic cleavage site, followed by a sequence motif identical to the N-terminal amino acid sequence of native active human SCCE. As in human SCCE the P2 position of the propeptide was occupied by an acidic amino acid residue, and the position corresponding to the suggested bottom of the primary substrate specificity pouch occupied by an asparagine residue. Analyses of mouse tissues by reverse transcriptase-polymerase chain reaction showed high expression in the skin, low expression in lung, kidney, brain, heart, and spleen, and no expression in liver or skeletal muscle. In situ hybridization of mouse skin showed expression in high suprabasal keratinocytes and in the luminal parts of hair follicles. Our results strongly suggest that we have cloned the murine analog of human SCCE cDNA.
...
PMID:Molecular cloning and tissue expression of the murine analog to human stratum corneum chymotryptic enzyme. 1046 96

The family of enzymes known as serine proteases supports many biological functions for cancer cells, including activation of growth and angiogenic factors and activation of other proteases for invasion and metastasis. In addition, many of these serine proteases are secreted by cells into the extracellular space to serve these functions. Therefore, serine proteases are excellent candidate tumor markers. To examine serine proteases expressed by ovarian carcinoma, we designed degenerate PCR primers corresponding to the conserved regions of these genes and used them in reverse transcriptase-PCR experiments with normal and tumor cDNA as a template. The PCR products were subcloned and sequenced, and one of these clones was found to encode a novel serine protease, named tumor-associated differentially expressed gene-14 (TADG14). Northern blot analysis indicated that the mRNA for TADG14 is 1.4 kb long and that it is highly overexpressed in ovarian carcinoma compared with normal ovary. The entire cDNA has been obtained, and based on sequence homology, it encodes a 260-amino acid serine protease. Semiquantitative PCR indicates that TADG14 is overexpressed in 24 of 40 tumors studied. Northern blot data confirm this overexpression, and immunohistochemical staining suggests that this protein is secreted. As such, the TADG14 protease may be useful as a diagnostic tool or as a molecular target for therapy.
...
PMID:Cloning of tumor-associated differentially expressed gene-14, a novel serine protease overexpressed by ovarian carcinoma. 1048 94

Dentin sialoprotein (DSP) and dentin phosphoprotein (DPP; phosphophoryn) are two principal dentin-specific non-collagenous proteins. DPP is extremely acidic and is rich in aspartic acid and serine. By virtue of this structure, DPP may bind large amounts of calcium and may facilitate initial mineralization of dentin matrix collagen as well as regulate the size and shape of the crystals. The function of DSP is not known. DSP and DPP are encoded by a single gene in both rat and mouse, and are uniquely expressed in odontoblasts and transiently in pre-ameloblasts. Because DSP and DPP are isolated from dentin as distinct proteins and appear to be present in different amounts, the nascent dentin sialophosphoprotein (DSPP) is likely cleaved to yield DSP and DPP. However, when, where and how the DSPP is cleaved into DSP and DPP is not clear. To further elucidate the structure and function of human DSP and DPP, we have cloned DPP and DSP cDNA by reverse transcriptase-polymerase chain reaction (RT-PCR) strategies, and then cloned and initiated characterization of a human dentin sialophosphoprotein gene. The genomic organization of human DSPP is very similar to that of mouse, containing five exons and four introns, suggesting it is a homologue of mouse dentin sialophosphoprotein (DSPP). Exons 1-4 encode for DSP, while exon 5 encodes for the C-terminus of DSP and the whole DPP. A 4.6-kb RNA transcript was detected on Northern blot analyses of total RNA extracted from immature (open root apices) human teeth using either a human DPP or DSP probe.
...
PMID:Molecular cloning of a human dentin sialophosphoprotein gene. 1070 75


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

---