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

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 50 S ribosome of Escherichia coli is partially degraded by RNase I in presence of a high concentration of Mg2+ (10 to 20 mM); the partially degraded subunit becomes resistant to the further action of RNase I. The latter remains latent in association with the subparticle as in case of 30 S ribosome (Neu, H.C., and Heppel, L.A. (1954) Proc. Natl. Acad. Sci. U.S.A. 51, 1267-1274). As a result of nucleolytic action, 23 S RNA is degraded to a smaller size and four proteins (L4, L10, L7/L12) are released from the subunit. From the location of these proteins, it appears that the primary site of action of RNase I is the central protuberance of the armchair model proposed for the subunit (Stoffler, G., and Whitman, H.G. (1977) in Molecular Mechanisms of Protein Biosynthesis (Weissbach, H., and Pestka, S., eds) pp. 117-144, Academic Press, New York).
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PMID:Site of action of RNase I on the 50 S ribosome of Escherichia coli and the association of the enzyme with the partially degraded subunit. 11 62

Skeletal muscle beta-tropomyosin, smooth muscle alpha-tropomyosin, and a low molecular weight fibroblast tropomyosin are generated by alternatively splicing RNA transcripts of the chicken tropomyosin 1 (TM 1) gene (Forry-Schaudies, S., Maihle, N. J., and Hughes, S. H. (1990) J. Mol. Biol. 211; 321-330). Two novel tropomyosin cDNAs that derive from mRNAs of the TM 1 gene have been isolated from a chicken embryo brain cDNA library. Brain cDNA BRT-1 is 2.2 kilobases in length and encodes 283 amino acids. It is identical to skeletal muscle beta-tropomyosin from amino acids 1 to 258. The sequence 3' of this point is unique to BRT-1; a comparison to genomic sequence indicates that a new carboxyl-terminal exon is used to generate this sequence. 1.4-kilobase brain cDNA BRT-2 contains sequences found in both fibroblast cDNA FT-beta (5'-end) and skeletal muscle cDNA SKT-beta (3'-end). RNase and S1 nuclease assays using RNA samples from leg muscle, gizzard, fibroblasts, and brain indicate that the TM 1 gene expresses four additional tropomyosin RNAs by alternately splicing previously characterized exons. These results demonstrate that the chicken TM 1 gene encodes nine tropomyosin RNAs through the use of two promoters, two internal exons that are mutually exclusive, and three 3'-exons. Implications for the regulation of alternative splicing are discussed.
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PMID:The chicken tropomyosin 1 gene generates nine mRNAs by alternative splicing. 185 15

The beta-adrenergic receptor kinase (beta ARK) specifically phosphorylates the agonist-occupied form of the beta-adrenergic and related G protein-coupled receptors. Structural features of this enzyme have been elucidated recently by the isolation of a cDNA that encodes bovine beta ARK. Utilizing a catalytic domain fragment of the beta ARK cDNA to screen a bovine brain cDNA library we have isolated a clone encoding a beta ARK-related enzyme which we have termed beta ARK2. Overall, this enzyme has 85% amino acid identity with beta ARK, with the protein kinase catalytic domain having 95% identity. The ability of beta ARK2 to phosphorylate various substrates was studied after expression in COS 7 cells. Although beta ARK2 is essentially equiactive with beta ARK in phosphorylating an acid-rich synthetic model peptide it was only approximately 50% as active when the substrate was the agonist-occupied beta 2-adrenergic receptor and only approximately 20% as active toward light-bleached rhodopsin. As with beta ARK, phosphorylation of the receptor substrates by beta ARK2 was completely stimulus dependent. RNA blot analysis with selected bovine tissues reveals an mRNA of 8 kilobases with a distribution similar to that of beta ARK. More detailed RNA analysis using a ribonuclease protection assay in various rat tissues suggests that the beta ARK2 message is present at much lower levels (typically 10-20%) than the beta ARK message. In the rat the beta ARK2 mRNA is localized predominantly in neuronal tissues although low levels are also observed in various peripheral tissues. The beta ARK2 gene has been localized to a region of mouse chromosome 5 whereas the beta ARK gene is localized on mouse chromosome 19. These data suggest the existence of a "family" of receptor kinases which may serve broadly to regulate receptor function.
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PMID:Cloning, expression, and chromosomal localization of beta-adrenergic receptor kinase 2. A new member of the receptor kinase family. 186 33

A cDNA clone, predicted to encode a variant form of the type 1 fibroblast growth factor receptor (FGFR1) containing a dipeptide Val-Thr (VT) deletion at amino acid positions 423 and 424 located within the juxtamembrane region, was isolated from a Xenopus embryo (stage 8 blastula) library. Sequence analysis of genomic DNA encoding a portion of the FGFR1 juxtamembrane region demonstrated that this variant form arises from use of an alternative 5' splice donor site. RNase protection analysis revealed that both VT- and VT+ forms of the FGFR1 were expressed throughout embryonic development, the VT+ being the major form. Amino acid position 424 is located within a consensus sequence for phosphorylation by a number of Ser/Thr kinases. We demonstrate that a VT+ peptide was specifically phosphorylated by protein kinase C (PKC) in vitro, but not by protein kinase A (PKA). A VT- peptide, on the other hand, was not a substrate for either enzyme. Phosphorylation levels of in vitro synthesized FGFR-VT+ protein by PKC were twice that of FGFR-VT- protein. In a functional assay, Xenopus oocytes expressing FGFR-VT- or FGFR-VT+ protein were equally able to mobilize intracellular Ca2+ in response to basic fibroblast growth factor (bFGF). However, pretreatment with phorbol 12-myristate 13-acetate significantly reduced this mobilization in oocytes expressing FGFR-VT+ while having little effect on oocytes expressing FGFR-VT-. These findings demonstrate that alternative splicing of Val423-Thr424 generates isoforms which differ in their ability to be regulated by phosphorylation and thus represents an important mechanism for regulating FGFR activity.
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PMID:Cloning of a fibroblast growth factor receptor 1 splice variant from Xenopus embryos that lacks a protein kinase C site important for the regulation of receptor activity. 755 2

The beta-adrenergic receptor kinase (beta ARK) specifically phosphorylates the agonist-occupied forms of the beta 2-adrenergic receptor and related G protein-coupled receptors. beta ARK is one of the best characterized members of a growing family of G protein-coupled receptor kinases. In this article we report the isolation and structural organization of the human beta ARK gene. The gene spans approximately 23 kilobases and is composed of 21 exons interrupted by 20 introns. Exon sizes range from 52 bases (exon 7) to over 1200 bases (exon 21), intron sizes from 68 bases (intron L) to 10.8 kilobases (intron A). The splice sites for donor and acceptor were in agreement with the canonical GT/AG rule. Functional regions of beta ARK are described with respect to their location within the exon-intron organization of the gene. Primer extension and RNase protection assays suggest a major transcription start site approximately 246 bases upstream of the start ATG. Sequence analysis of the 5'-flanking/promoter region reveals many features characteristic of mammalian housekeeping genes, i.e. the lack of a TATA box, an absent or nonstandard positioned CAAT box, high GC content, and the presence of Sp1-binding sites. The extraordinarily high GC content of the 5'-flanking region (> 80%) helps define this region as a CpG island that may be a principal regulator of beta ARK expression.
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PMID:Structure of the human gene encoding the beta-adrenergic receptor kinase. 819 24

Two frog egg lectins [Rana catesbeiana lectin (SBL-C) and Rana japonica lectin] preferentially agglutinate a large variety of human and animal tumor cells but not blood cells, lymphocytes, or fibroblasts. These lectins belong to the superfamily of pyrimidine base-specific RNases. The two lectins bound to a heparin-Sepharose column and were eluted from the column by an increase of NaCl molarity. Both their tumor cell-agglutinating activity and RNase activity were inhibited by heparin, and also by polyamines, such as spermine. Both lectins inhibited P388 leukemia cell proliferation. The inhibitory activity of SBL-C was blocked by addition of heparin. SBL-C inhibited protein synthesis by P388 cells, but RNase A did not. No lectin-induced antiproliferative effect was observed after sialidase treatment of cells. The antiproliferative activity of SBL-C was also inhibited by ammonium chloride treatment. These results suggest that internalization of the lectins by lectin receptor (sialoglycoconjugate)-mediated endocytosis is followed by cell death due to inhibition of protein synthesis. Administration of SBL-C i.p. delayed time to death in mice receiving i.p. transplants of Sarcoma 180 and Mep II cells.
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PMID:Inhibition of cell proliferation by Rana catesbeiana and Rana japonica lectins belonging to the ribonuclease superfamily. 831 82

Wilms tumor is a pediatric neoplasm that arises from the metanephric blastema. The expression of the gene encoding insulin-like growth factor II (IGF-II) is often elevated in these tumors. Since many of the actions of IGF-II are mediated through activation of the IGF-I receptor (IGF-IR), we have measured the levels of IGF-IR mRNA in normal kidney and in Wilms tumor samples using solution hybridization/RNase protection assays. IGF-IR mRNA levels in the tumors were 5.8-fold higher than in adjacent normal kidney tissue. Among the tumors themselves, the levels of IGF-IR mRNA in those containing heterologous stromal elements were 2-fold higher (P < 0.01) than in tumors without these elements. IGF-IR gene (designated IGF1R) expression in the tumors was inversely correlated with the expression of the Wilms tumor suppressor gene WT1, whose inactivation appears to be a key step in the etiology of Wilms tumor. Cotransfection of Chinese hamster ovary cells with rat and human IGF-IR gene promoter constructs driving luciferase reporter genes and with WT1 expression vectors showed that the active WT1 gene product represses IGF-IR promoter activity in a dose-dependent manner. These results suggest that underexpression, deletion, or mutation of WT1 may result in increased expression of the IGF-IR, whose activation by IGF-II may be an important aspect of the biology of Wilms tumor.
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PMID:Increased expression of the insulin-like growth factor I receptor gene, IGF1R, in Wilms tumor is correlated with modulation of IGF1R promoter activity by the WT1 Wilms tumor gene product. 839 Jun 84

The distribution of neutral endopeptidase (NEP; EC 3.4.24.11) was examined in the alimentary tract of the rat. Immunoreactive NEP and NEP mRNA were localized to epithelial cells of the small intestine and to muscle cells in the stomach, small intestine, and colon by immunohistochemistry and in situ hybridization histochemistry. NEP antisera recognized a protein on Western blots of membranes from gastric, jejunal, and colonic mucosa and gastric muscle with an electrophoretic mobility identical to that of recombinant human NEP (approximately 95 kDa). An antisense cRNA probe to NEP hybridized to RNA of approximately 3.5 kb and approximately 6.5 kb, corresponding to the primary transcripts of rat NEP, on Northern blots of total RNA from the jejunal mucosa. NEP message was detected in mRNA from jejunal and colonic mucosa and gastric, jejunal, and colonic muscle using a ribonuclease protection assay. NEP enzymatic activity, assessed by DL-thiorphan-inhibitable degradation of glutaryl-Ala-Ala-Phe-4-methoxy-2-naphthylamine, was highest in homogenates of jejunal mucosa (868 +/- 98 pmol.h-1 x micrograms protein-1) and was between 49- and 413-fold lower in other gastrointestinal tissues. The cellular origin of NEP in the gastric and colonic mucosa could not be determined.
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PMID:Distribution and abundance of neutral endopeptidase (EC 3.4.24.11) in the alimentary tract of the rat. 846 Jul 3

Normal expression of the hematopoietic growth factor receptor FLT3 (STK-1@Flk2) is limited to CD34+ stem/progenitor cells. We have evaluated the expression of FLT3 by RNase protection assay and Western blotting in 161 primary bone marrow (BM) samples from patients with leukemia. FLT3 RNA was found to be expressed at a higher level than in normal BM controls in 33 of 33 B-lineage acute leukemias, 11 of 12 acute myeloid leukemias (AMLs), and 3 of 11 T-cell acute leukemias (T-ALLs). Expression of FLT3 RNA was also observed in some cases of blast crisis CML. The FLT3 signal resulted from expression on the leukemic blasts, and was not caused by increased FLT3 expression on normal CD34+ stem/progenitor cells in the leukemic samples. To determine if FLT3 protein was also overexpressed, proteins were extracted from leukemic BM samples and screened by Western blotting with anti-FLT3 antisera. FLT3 protein was not detected in normal BM controls, but was found in 14 of 14 B-lineage ALLs, 36 of 41 AMLs, and 1 of 4 T-ALLs. Stimulation of patient samples with FLT3 ligand resulted in autophosphorylation of the FLT3 receptor, suggesting the receptor is functional in these cells. These data show that FLT3 RNA and protein are aberrantly expressed by AML and ALL cells in that CD34 expression and FLT3 expression are no longer synchronous, and suggest the possibility that overexpression of FLT3 could play a role in the survival and/or proliferation of malignant clones in acute myeloid and lymphoid leukemias.
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PMID:Expression of the hematopoietic growth factor receptor FLT3 (STK-1/Flk2) in human leukemias. 856 34

The genomic organization of Cek5, a receptor tyrosine kinase of the Eph subfamily, was elucidated utilizing a strategy involving PCR amplification of Cek5 genomic DNA. Cek5 is the first Eph-related kinase for which the exon-intron structure of the entire coding region has been determined. The Cek5 gene spans over 35 kb and comprises at least 16 exons. The exon-intron structure of Cek5 can be correlated with the proposed domain structure of the Eph subfamily, with the exception of an Ig motif in the extracellular domain. Intron positions in the Cek5 gene coincide with the locations of the deletions, substitutions, or insertions that have been described in a number of Eph-related kinases. This suggests that alternative processing plays a major role in generating the structural variability observed in the Eph subfamily. Consistent with this hypothesis, analysis of the Cek5 gene indicate that: (i) a variant form of Cek5 containing an insertion in the juxtamembrane region (Cek5 +) arises through the use of alternative 5' splice sites, and (ii) a soluble form of Cek5 comprising only the extracellular domain (Cek5s) may exists, which originates by alternative polyadenylation. RT-PCR analysis and RNase protection assays revealed the expression of both Cek5 + and Cek5s at various stages of chicken development.
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PMID:Genomic organization and alternatively processed forms of Cek5, a receptor protein-tyrosine kinase of the Eph subfamily. 857 Jan 95


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