title: p27x-III and p21x-III, proteins encoded by the pX sequence of human T-cell leukemia virus type I.
abstract: Human T-cell leukemia virus type I (HTLV-I) is an etiological agent of adult T-cell leukemia and has a unique sequence, pX, that contains four possible open reading frames, I-IV. p40x was previously identified as the gene product of frame IV (x-lor) and was suggested to mediate transcriptional trans-activation of the viral long terminal repeats. We have identified two pX gene products, p27x-III and p21x-III, encoded by frame III, which mostly overlapped frame IV. These proteins were detected with rabbit antiserum against the synthetic peptide predicted from the 3' end of frame III. p27x-III is phosphorylated in cultured cells, and the phosphoprotein (pp27x-III) is localized in nuclei; some pp27x-III was tightly bound to nuclear components. p27x-III was detected in a number of cell lines that express other viral antigens, including a cell line previously reported to express only p40x as a viral protein. The function(s) of p27x-III and p21x-III is not known, but the tight binding of pp27x-III to nuclear components suggests that it is associated with regulation of viral gene expression.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D017977:Deltaretrovirus / Q000032:analysis / Q000235:genetics*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D005814:Genes, Viral; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D008970:Molecular Weight; D010750:Phosphoproteins / Q000235:genetics*; D011499:Protein Processing, Post-Translational; D012191:Retroviridae Proteins / Q000235:genetics*; D013601:T-Lymphocytes / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D006023:Glycoproteins; D010750:Phosphoproteins; D012191:Retroviridae Proteins; D014764:Viral Proteins