Evidence for phosphorylation oftrans-activator p40x of human T-cell leukemia virus type I produced in insect cells with a baculovirus expression vector

Hiroshi Nyunoya, Tsuyoshi Akagi, Tsutomu Ogura, Susumu Maeda, Kunitada Shimotohno

Research output: Contribution to journalArticle

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Abstract

Human T-cell leukemia virus type I (HTLV-I) encodes a trans-activator protein p40x which positively regulates transcription of the viral RNA as well as interleukin-2 and its receptor genes. We placed a cDNA coding for p40x in baculovirusBombyx mori nuclear polyhedrosis virus (BmNPV) expression vectors. Infection of BmN cells derived from an insect,B. mori (silkworm), with a recombinant virus led to the production of soluble p40x. The biological activity of the recombinant p40x was demonstrated by introducing the protein into intact NIH 3T3 cells that had been selected for genomic integration of HTLV-I LTR connected with the CAT gene. Immunocytochemical and cell fractionation analyses showed the localization of p40x in both the cytoplasmic and nuclear fractions of BmN cells. Analyses of32P-labeled proteins of BmN cells by cell fractionation and subsequent immunoprecipitation revealed that the p40x present in each subcellular fraction was phosphorylated. The post-translational modification was inhibited by the addition of a protein kinase inhibitor K252a during the metabolic labeling of BmN cells. Phosphoamino acid analysis indicated that the phosphorylation occurred on serine residues of p40x.

Original languageEnglish
Pages (from-to)538-544
Number of pages7
JournalVirology
Volume167
Issue number2
DOIs
Publication statusPublished - 1988
Externally publishedYes

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Human T-lymphotropic virus 1
Baculoviridae
Insects
Phosphorylation
Cell Fractionation
Morus
tax Gene Products
Phosphoamino Acids
Nucleopolyhedrovirus
NIH 3T3 Cells
Bombyx
Subcellular Fractions
Interleukin-2 Receptors
Viral RNA
Post Translational Protein Processing
Protein Kinase Inhibitors
Immunoprecipitation
Serine
Genes
Proteins

ASJC Scopus subject areas

  • Virology

Cite this

Evidence for phosphorylation oftrans-activator p40x of human T-cell leukemia virus type I produced in insect cells with a baculovirus expression vector. / Nyunoya, Hiroshi; Akagi, Tsuyoshi; Ogura, Tsutomu; Maeda, Susumu; Shimotohno, Kunitada.

In: Virology, Vol. 167, No. 2, 1988, p. 538-544.

Research output: Contribution to journalArticle

Nyunoya, Hiroshi ; Akagi, Tsuyoshi ; Ogura, Tsutomu ; Maeda, Susumu ; Shimotohno, Kunitada. / Evidence for phosphorylation oftrans-activator p40x of human T-cell leukemia virus type I produced in insect cells with a baculovirus expression vector. In: Virology. 1988 ; Vol. 167, No. 2. pp. 538-544.
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