Abstract. This paper describes our work in integrating three different lexical resources: FrameNet, VerbNet, and WordNet, into a unified, richer knowledge-base, to the end of enabling more robust semantic parsing. The construction of each of these lexical resources has required many years of laborious human effort, and they all have their strengths and shortcomings. By linking them together, we build an improved resource in which (1) the coverage of FrameNet is extended, (2) the VerbNet lexicon is augmented with frame semantics, and (3) selectional restrictions are implemented using WordNet semantic classes. The synergistic exploitation of various lexical resources is crucial for many complex language processing applications, and we prove it once again effective in building a robust semantic parser.
Borna disease virus (BDV) is a newly classified nonsegmented negative-strand RNA virus (order of Mononegavirales) that persistently infects specific brain regions and circuits of warm-blooded animals to cause behavioral disturbances. Viruses within the order of Mononegavirales have phosphoproteins that typically serve as transcription factors and are modulated in functional activity through phosphorylation. To identify the kinases involved in BDV phosphoprotein (BDV-P) phosphorylation, in vitro phosphorylation assays were performed using recombinant phosphoprotein produced in Escherichia coli as substrate and cytoplasmic extracts from a rat glioma cell line (C6) or rat brain extracts as sources of kinase activity. These experiments revealed that BDV-P was phosphorylated predominantly by protein kinase C (PKC) and to a lesser extent by casein kinase II. Partial purification of the PKC from rat brain extract suggested that the BDV-P phosphorylating kinase is PKC⑀. A role for PKC phosphorylation in vivo was confirmed by using the PKCspecific inhibitor GF109203X. Furthermore, peptide mapping studies indicated that BDV-P is phosphorylated at the same sites in vitro as it is in vivo.
Borna disease virus (BDV)1 is the prototype of a new family, Bornaviridae, within the nonsegmented negative-strand RNA viruses (Mononegavirales) (1, 2), which is characterized by low productivity, neurotropism (3, 4), a nuclear localization for transcription and replication (5, 6), and posttranscriptional modification of subgenomic RNAs by splicing (7,8). The potential host range for BDV is likely to include all warm-blooded animals. Accumulating evidence suggests that it may be a human pathogen (9 -15).Phosphoproteins of nonsegmented negative-strand RNA viruses are typically integral components of the viral polymerase complex (16). The activity of these proteins, and in some cases their three-dimensional structure, is dependent upon phosphorylation (17)(18)(19)(20). Casein kinase II (CKII)-mediated phosphorylation of VSV-P leads to its multimerization in vitro and promotes transcription (17,20), possibly by facilitating binding of VSV-P to the VSV polymerase (21). In human respiratory syncytial virus (RSV), CKII-mediated phosphorylation of phosphoprotein is also a prerequisite for transcriptional activity (18,22). Although the human parainfluenza virus type 3 (HPIV3) phosphoprotein is phosphorylated by protein kinase C (PKC) rather than by CKII (19), the effect of HPIV3 phosphoprotein phosphorylation is similar in significance to phosphorylation of VSV-P and RSV phosphoprotein; inhibition of PKC by pseudopeptides results in abrogation of viral replication (19).Because phosphorylation of the BDV phosphoprotein (BDV-P) is likely to be an important step in the life cycle of BDV we have identified the kinases involved in this process and mapped the BDV-P phosphorylation sites. Our findings indicate that BDV-P is phosphorylated predominantly by PKC⑀ and to a lesser extent by CKII.
EXPERIMENTAL PROCEDURESIn Vivo Phosphorylation Experiments-BD...
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