We have cloned and sequenced a cDNA encoding gp34, a novel glycoprotein expressed in cells bearing human T-cell leukemia virus type I (HTLV-I). HTLV-I has a trans-acting transcriptional activator, p40tax, that is thought to be implicated in leukemogenesis through the activation of cellular enhancers. With a subline (JPX-9) of the human T-celi line Jurkat, in which p40 is inducible, gp34 was shown to be of cellular origin and to be transcriptionally activated by p40. It was also demonstrated that two species of mRNA are generated from one copy of the gp34 gene and that these mRNAs encode the identical gp34 product and differ in the 3' untranslated region. Analysis of the deduced amino acid sequence of gp34 showed that it lacks typical signal peptides; however, it has a hydrophobic stretch for membrane anchoring and four possible N-linked glycosylation sites at the carboxy-terminal portion, indicating that it belongs to the family of membrane proteins whose carboxy-terminal portion protrudes out of the cell. The gp34 gene displayed relatively delayed induction compared with other genes activated by p40. Taken together with the observation of the dependence of gp34 expression on HTLV-I p40, unlike other p4Otax-dependent genes such as those for the interleukin-2 receptor a chain and c-fos, which are expressed or induced under physiological conditions, we predict that the mechanism involved in the induction of gp34 expression by p40 is distinct from and more intricate than those for the previously characterized genes.

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The chromosomal inversion (16)(p13q22), which is associated with the M4-eosinophilia subtype of human acute myeloid leukemia, causes the fusion of two distinct genes

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The chromosomal inversion 16(p13;q22) associated with human acute myeloid leukemia generates the chimeric PEBP2b/CBFb-SMMHC gene. The PEBP2b/CBFb portion of the chimeric polypeptide harbors most of the amino acid sequence of the PEBP2b/CBFb protein, the non-DNA binding subunit of the heterodimeric transcription factor, PEBP2/CBF, whereas the SMMHC portion of the chimera consists of the rod domain of the smooth muscle myosin heavy chain molecule. In this study we examined the subcellular localization of the chimeric protein and its e ect both on stress ®bers and transcriptional activation by transfecting cDNA into tissue culture cells. The localization of the chimera was investigated by immunocytochemical staining of cells and was found to be both cytoplasmic and nuclear. One aspect of the e ect of expression of the chimera was a drastic alteration of cell morphology. The cells appeared elongated and possessed long cytoplasmic processes. Double¯uorescent labeling revealed disorganization of the stress ®bers and an altered F-actin staining pattern in the transfected cells. Studies using a deletion mutant showed that both the PEBP2b/CBFb and SMMHC domains are necessary for the induction of the morphological alteration. A signi®cant proportion of the chimeric protein was retained in the cytoskeleton after detergent extraction of the cells and could be recuperated as a membrane fraction, suggesting that this is one of the probable sites of action of the PEBP2b/ CBFb-SMMHC protein. Another e ect of the chimeric protein was inhibition of transcriptional activation dependent on the PEBP2/CBF binding DNA sequence. However, deregulation of PEBP2/CBF site dependent transcription by itself was not su cient to induce cell morphological changes. Taken together, these results indicate that the PEBP2b/CBFb-SMMHC chimeric protein acts at two levels, at the level of stress ®ber organization and at the level of transcriptional activation. We suggest that the action of PEBP2b/CBFb-SMMHC depends to a great extent on whether it is located in the cytoplasm or in the nucleus.

The red coloration of the mango 'Irwin' skin is an important factor determining its value in the Japanese domestic luxury fruit market. In the present study, to investigate the molecular mechanism underlying anthocyanin biosynthesis of mango fruit skin, UFGT-like genes were isolated and the expression profile of anthocyanin-related genes was determined. Several UFGT-like genes were identified in transcriptome data of red 'Irwin' mango skin and two genes, MiUFGT1 and MiUFGT3, were considered to be involved in mango skin coloration. Deduced amino acid sequences of these genes exhibited high similarity to other plant UFGTs and contained the conserved PSPG box common to the glycosyltransferase family. The presence of a glutamine and a histidine residue at the C-terminus end of the PSPG box in MiUFGT1 and MiUFGT3, respectively, implied that MiUFGT1 and MiUFGT3 use glucose and galactose, respectively, as a sugar donor; however, the actual function and sugar donor preference of these enzymes remain to be elucidated. Expression analysis of anthocyanin-related genes during skin coloration suggested that MiCHS and MiANS, as well as MiUFGT1 and MiUFGT3, play important roles in the anthocyanin biosynthesis of mango fruit skin and that the expression of these genes is regulated by the MYB transcription factor, as reported in other plant species.

TBP-like protein (TLP) is involved in transcriptional activation of an upstream promoter of the human p21 gene. TLP binds to p53 and facilitates p53-activated transcription from the upstream promoter. In this study, we clarified that in vitro affinity between TLP and p53 is about one-third of that between TBP and p53. Extensive mutation analyses revealed that the TLP-stimulated function resides in transcription activating domain 1 (TAD1) in the N-terminus of p53. Among the mutants, #22.23, which has two amino acid substitutions in TAD1, exhibited a typical mutant phenotype. Moreover, #22.23 exhibited the strongest mutant phenotype for TLP-binding ability. It is thus thought that TLP-stimulated and p53-dependent transcriptional activation is involved in TAD1 binding of TLP. #22.23 had a decreased transcriptional activation function, especially for the upstream promoter of the endogenous p21 gene, compared with wild-type p53. This mutant did not facilitate p53-dependent growth repression and etoposide-mediated cell-death as wild-type p53 does. Moreover, mutation analysis revealed that middle part of TLP, which is requited for p53 binding, is involved in TLP-stimulated and p53-dependent promoter activation and cell growth repression. These results suggest that activation of the p21 upstream promoter is mediated by interaction between specific regions of TLP and p53.