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T Raabe

Publications and source records attributed to T Raabe.

35 records · Page 2Linked to original sources
PubMed1994

Genetic dissection of signal transduction mediated by the sevenless receptor tyrosine kinase in Drosophila.

The specification of the R7 photoreceptor cell fate in the developing eye of Drosophila depends on the local activation of the sevenless (sev) receptor tyrosine kinase by boss, a protein expressed on the membrane of the neighboring R8 cell. Constitutive activation of the sev receptor results in a dosage dependent increase in the number of R7 cells per ommatidium. Genetic screens have been used to identify mutations that alter the efficiency of signal transduction. Subsequent molecular characterization of the corresponding genes has led to the identification of a number of proteins involved in transducing the signal from the receptor to the nucleus. In contrast to the receptor and its ligand, these components are shared between different signal transduction pathways not only in Drosophila but are also homologous to components involved in signal transduction in other organisms.

Animals↗
PubMed1994

Poly(A) polymerase contains multiple functional domains.

Poly(A) polymerase (PAP) contains regions of similarity with several known protein domains. Through site-directed mutagenesis, we provide evidence that PAP contains a functional ribonucleoprotein-type RNA binding domain (RBD) that is responsible for primer binding, making it the only known polymerase to contain such a domain. The RBD is adjacent to, and probably overlaps with, an apparent catalytic region responsible for polymerization. Despite the presence of sequence similarities, this catalytic domain appears to be distinct from the conserved polymerase module found in a large number of RNA-dependent polymerases. PAP contains two nuclear localization signals (NLSs) in its C terminus, each by itself similar to the consensus bipartite NLS found in many nuclear proteins. Mutagenesis experiments indicate that both signals, which are separated by nearly 140 residues, play important roles in directing PAP exclusively to the nucleus. Surprisingly, basic amino acids in the N-terminal-most NLS are also essential for AAUAAA-dependent polyadenylation but not for nonspecific poly(A) synthesis, suggesting that this region of PAP is involved in interactions both with nuclear targeting proteins and with nuclear polyadenylation factors. The serine/threonine-rich C terminus is multiply phosphorylated, including at sites affected by mutations in either NLS.

Amino Acid Sequence↗
PubMed1993

Genetic dissection of signal transduction mediated by the sevenless receptor tyrosine kinase in Drosophila.

The specification of the R7 photoreceptor cell fate in the developing eye of Drosophila depends on the local activation of the sevenless (Sev) receptor tyrosine kinase by Boss, a protein expressed on the membrane of the neighbouring R8 cell. Constitutive activation of the Sev receptor results in a dosage-dependent increase in the number of R7 cells per ommatidium. Genetic screens have been used to identify mutations that alter the efficiency of signal transduction. Subsequent molecular characterization of the corresponding genes has led to the identification of a number of proteins involved in transducing the signal from the receptor to the nucleus. In contrast to the receptor and its ligand, these components are shared between different signal transduction pathways not only in Drosophila but are also homologous to components involved in signal transduction in other organisms.

Animals↗
PubMed1993

A Drosophila SH2-SH3 adaptor protein implicated in coupling the sevenless tyrosine kinase to an activator of Ras guanine nucleotide exchange, Sos.

A Drosophila gene (drk) encodes a widely expressed protein with a single SH2 domain and two flanking SH3 domains, which is homologous to the Sem-5 protein of C. elegans and mammalian GRB2. Genetic analysis suggests that drk function is essential for signaling by the sevenless receptor tyrosine kinase. Drk biological activity correlates with binding of its SH2 domain to activated receptor tyrosine kinases and concomitant localization of drk to the plasma membrane. In vitro, drk also binds directly to the C-terminal tail of Sos, a Ras guanine nucleotide-releasing protein (GNRP), which, like Ras1 and drk, is required for sevenless signaling. These results suggest that drk binds autophosphorylated receptor tyrosine kinases with its SH2 domain and the Sos GNRP through its SH3 domains, thereby coupling receptor tyrosine kinases to Ras activation. The conservation of these signaling proteins during evolution indicates that this is a general mechanism for linking tyrosine kinases to Ras.

Amino Acid Sequence↗
PubMed1993

Nucleotide sequence of the human coronavirus 229E RNA polymerase locus.

The nucleotide sequence of the human coronavirus 229E (HCV 229E) RNA polymerase gene and the 5' region of the genome has been determined. The polymerase gene is comprised of two large open reading frames, ORF1a and ORF1b, that contain 4086 and 2687 codons, respectively. ORF1b overlaps ORF1a by 43 bases in the (-1) reading frame. The in vitro translation of SP6 transcripts which include HCV 229E sequences encompassing the ORF1a/ORF1b junction show that expression of ORF1b can be mediated by ribosomal frame-shifting. The predicted translation products of ORF1a (454,200 molecular weight) and ORF1a/1b (754,200 molecular weight) have been compared to the predicted RNA polymerase gene products of infectious bronchitis virus (IBV) and murine hepatitis virus (MHV) and conserved structural features and putative functional domains have been identified. This analysis completes the nucleotide sequence of the HCV 229E genome.

Amino Acid Sequence↗
PubMed1993

Characterization of the human coronavirus 229E (HCV 229E) gene 1.

The sequence of the HCV 229E gene 1 has been determined and compared with the homologous sequences of the murine hepatitis virus and the avian infectious bronchitis virus. The coding sequence of gene 1 is 20,273 nucleotides in length. Within this coding region are two large open reading frames, ORF 1a (4,086 codons) and ORF 1b (2,687 codons) which overlap by 40 nucleotides. In the overlapping region, the genomic RNA can be folded into a pseudoknot structure, an element which is known to mediate -1 ribosomal frame-shifting in other coronaviruses. Assuming that -1 frame-shifting occurs at the HCV sequence UUUAAAC (nucleotides 12,514-12,520), the ORF 1a - ORF 1b product is predicted to be 6,758 amino acids in length. Our sequence analysis of the HCV 229E gene 1 has revealed a high degree of similarity within the ORF 1b of HCV, MHV and IBV, whereas ORF 1a is much less conserved. Elements which are believed to be necessary for specific (e.g. frame-shifting) and general (e.g. NTP-binding/helicase) transcriptional functions have been identified. This study completes the genomic sequence of HCV 229E which is 27.27 kb long and one of the largest known RNA genomes.

Base Sequence↗
PubMed1993

Molecular analysis of the human coronavirus (strain 229E) genome.

The nucleotide sequence of the human coronavirus strain 229E (HCV 229E) has been determined. This article describes the organization of the virus genome, the predicted viral gene products and the mechanisms which regulate viral gene expression. This information provides a basis to investigate the biology and pathogenesis of HCV.

Amino Acid Sequence↗
PubMed1993

Genetic analysis of the sevenless signal transduction pathway of Drosophila.

The specification of the R7 photoreceptor cell fate in the developing eye of Drosophila depends on the local activation of the sevenless (sev) receptor tyrosine kinase (RTK) by boss, a protein expressed on the membrane of the neighboring R8 cell. Constitutive activation of the sev receptor results in a dosage dependent increase in the number of R7 cells per ommatidium. Genetic screens have been used to identify mutations that alter the efficiency of signal transduction. Subsequent molecular characterization of the corresponding genes has led to the identification of a number of proteins involved in transducing the signal from the receptor to the nucleus. In contrast to the receptor and its ligand, these components are shared between different signal transduction pathways not only in Drosophila but homologous components are also involved in signal transduction in other organisms.

Animals↗
PubMed1991

Primary structure and expression of bovine poly(A) polymerase.

Poly(A) polymerase has a critical role in the synthesis of messenger RNA in eukaryotic cells. The isolation and characterization of complementary DNAs encoding bovine poly(A) polymerase is described here. The predicted sequences of the mRNA and protein reveal features that provide insights into how the enzyme functions and how it might be regulated. Poly(A) polymerase expressed from a cloned cDNA is fully functional in in vitro assays, and mutational analyses have identified a putative regulatory domain that enhances, but is not essential for, activity.

Amino Acid Sequence↗
PubMed1991

The rat interleukin-5 gene: characterization and expression by retroviral gene transfer and polymerase chain reaction.

The rat interleukin-5 (IL-5) gene was isolated from a genomic lambda phage library and a fragment containing all four exons was inserted into the retroviral vector pXT1, resulting in pXTRIL5. Upon retroviral gene transfer into two IL-5-dependent mouse cell lines, B13 and T88M, autonomously growing cells were established and B-cell growth factor activity was detected in the supernatants of the infected cells. "cDNA" versions of the rat IL-5 gene were rescued by the polymerase chain reaction (PCR) with primers specific for the flanking regions of the cloning site in pXT1. Restriction or DNA sequence analysis of five different clones revealed precise splicing in two cases, while three of the clones had retained the first intron. In addition, in two of these about 400 bp of rat IL-5 5' flanking regions were deleted. The sequence comparison of rat, mouse, and human IL-5 genes revealed a high degree of conservation (e.g., mouse and rat were 92% homologous at the amino acid level). The combination of retroviral gene transfer and PCR may offer an alternative, efficient method for the cloning of cDNAs.

Amino Acid Sequence↗
PubMed1990

Characterization of a nucleic acid probe for the diagnosis of human coronavirus 229E infections.

A cDNA copy of the HCV229E nucleocapsid protein gene was isolated and characterized. Sequence analysis predicts a nucleocapsid polypeptide of 389 amino acids with a molecular weight (mol. wt.) of 43,450. Single strand RNA probes derived from the cDNA copy hybridize specifically to HCV229E RNA and approximately 50 pg of intracellular viral RNA can be readily detected. The application of nucleic acid hybridization as a routine procedure for the diagnosis of HCV229E infection is discussed.

Amino Acid Sequence↗
PubMed1990

Nucleotide sequence of the gene encoding the spike glycoprotein of human coronavirus HCV 229E.

The gene encoding the spike glycoprotein of the human coronavirus HCV 229E has been cloned and sequenced. This analysis predicts an S polypeptide of 1173 amino acids with an Mr of 128,600. The polypeptide has 30 potential N-glycosylation sites. A number of structural features typical of coronavirus S proteins can be recognized, including a signal sequence, a membrane anchor, heptad repeat structures and a carboxy-terminal cysteine cluster. A detailed, computer-aided comparison with the S proteins of infectious bronchitis virus, feline infectious peritonitis virus, transmissible gastroenteritis virus and murine hepatitis virus, strain JHM is presented. We have also done a Northern blot analysis of viral RNAs in HCV 229E-infected cells using synthetic oligonucleotides. On the basis of this analysis, and by analogy to the replication strategy of other coronaviruses, we are able to propose a model for the organization and expression of the HCV 229E genome.

Amino Acid Sequence↗
PubMed1989

Nucleotide sequence of the gene encoding the membrane protein of human coronavirus 229 E.

The sequence of the gene encoding the membrane protein of human coronavirus 229 E (HCV 229 E) has been determined. The primary translation product, deduced from the DNA sequence, is a polypeptide of 225 amino acids with a predicted molecular weight of 26,000. The polypeptide has 3 potential N-glycosylation sites. Many structural similarities with the membrane proteins of other coronaviruses can be recognized.

Amino Acid Sequence↗
PubMed1988

A selection cartridge for rapid detection and analysis of spontaneous mutations including insertions of transposable elements in Enterobacteriaceae.

We present a method that allows positive selection and rapid analysis of mutations in Enterobacteriaceae. Mutations are detected in a 2630 bp selection cartridge inserted in two different bacterial multicopy plasmid vectors. Spontaneous mutations in Escherichia coli, Enterobacter cloacae and Citrobacter freundii include insertions, deletions and point mutations. The small size of the target sequence facilitates rapid analysis of DNA rearrangements by cleavage with restriction enzymes and of any type of mutation by DNA sequence analysis. While in E. coli insertions of the mobile elements IS1, IS2 and IS5 were readily found, insertions of putative new transposable elements were detected in Enterobacter cloacae. The selection cartridge can thus serve as a tool for studying the spectrum of insertion mutations in Enterobacteriaceae and probably other Gram-negative bacteria, and the dependency of this spectrum on physiological and environmental factors and the host's genetic background can be investigated.

Base Sequence↗
PubMed1988

Identification of the coronavirus MHV-JHM mRNA 4 product.

A bacterial expression vector was constructed to encode a fusion protein which had, at its carboxy terminus, a polypeptide encoded within the 5' proximal open reading frame of the coronavirus MHV-JHM mRNA 4. This polypeptide was isolated and used to produce an antiserum. The antiserum reacted specifically with a 15,000 Mr polypeptide synthesized in MHV-JHM-infected cells, or in vitro translations of infected cell poly(A) RNA enriched for mRNA 4. These results demonstrate the translational activity of mRNA 4 during infection, identify conclusively the translation product and provide a means to investigate the synthesis and function of this protein.

Antibodies, Viral↗