title: The p40x of human T-cell leukemia virus type I is a trans-acting activator of viral gene transcription.
abstract: Human T-cell leukemia virus type I has a unique sequence pX and the product p40x was proposed to be a specific trans-acting transcriptional activator of expression of the viral gene. Recently, a second pX protein p27x-III in addition to p40x was identified; these two proteins are encoded by overlapping frames III and IV (x-lor). For determination of which product is the trans-acting activator, site-directed mutations were introduced into the pX sequence which was placed under the metallothionein promoter. On cotransfection with pLTR-CAT (a plasmid containing the LTR of HTLV-I and chloramphenicol acetyltransferase gene), only the mutations that affected p40x expression inactivated the transcriptional activation from the LTR.
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D017977:Deltaretrovirus / Q000235:genetics*; D005786:Gene Expression Regulation; D005814:Genes, Viral; D009154:Mutation; D010750:Phosphoproteins / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D010750:Phosphoproteins; D014157:Transcription Factors; D014764:Viral Proteins