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Mosquito homolog of the La autoantigen binds to Sindbis virus RNA

Pardigon, Nathalie and Strauss, James H. (1996) Mosquito homolog of the La autoantigen binds to Sindbis virus RNA. Journal of Virology, 70 (2). pp. 1173-1181. ISSN 0022-538X. PMCID PMC189926.

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We have isolated a 50-kDa mosqoito protein that binds with high affinity to a riboprobe representing the 3' end of the minus strand of Sindbis virus RNA, The isolated protein has been used to obtain cDNA clones encoding this protein that have been sequenced and used to express the protein in large amounts, Sequence comparisons make clear that this protein is the mosquito homolog of the La autoantigen, The N-terminal half of the protein shares considerable sequence identity with the human La protein, the rat La protein, and the recently identified Drosophila melanogaster homolog, There is one stretch of 100 amino acids in the N-terminal domain in which 48 residues are identical in all four proteins, In contrast, the C-terminal domain of the mosquito protein shares little identity with any of the other three proteins, We have also shown that the mosquito protein, the human protein, and a putative chicken homolog of the La protein cross-react immunologically and, thus, all share antigenic epitopes, The mosquito La protein is primarily nuclear in location, but significant amounts are present in the cytoplasm, as is the case for the La proteins of other species, The equilibrium constant for the binding of the expressed mosquito La protein to the Sindbis virus riboprobe is 15.4 nM, and thus the affinity of binding is high enough to be physiologically relevant, Furthermore, the conservation of this protein in the animal kingdom may be significant, because Sindbis virus utilizes mosquitoes, birds, and mammals as hosts, We propose that the interactions we observe between the La protein and a putative promoter in the Sindbis virus genome are significant for Sindbis virus RNA replication.

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Additional Information:© 1996, American Society for Microbiology. Received 10 August 1995; accepted 13 November 1995. We thank D. Krapf and the Caltech microsequencing facility for help with rHPLC separation and outstanding microsequencing. We are grateful to D. Kenan for providing the patient anti-La serum as well as for help with the protein alignment, to S. Wolin for sharing the Drosophila La sequence prior to publication, and to G. Ludwig for his mosquito cDNA library. We thank J. Campbell and R. Verma for help in the design of the protein purification and E. Davidson and J. Moore for helpful discussions about binding assays and quantitation. We are also grateful to J. Bradley for help with the immunofluorescence. This work was supported by grant DMB-9104054 from the National Science Foundation and grant AI 10793 from the National Institutes of Health.
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NIHAI 10793
Issue or Number:2
PubMed Central ID:PMC189926
Record Number:CaltechAUTHORS:PARjvir96
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:4560
Deposited By: Lindsay Cleary
Deposited On:29 Aug 2006
Last Modified:02 Oct 2019 23:14

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