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Nearly 7000 Arabidopsis thaliana-expressed sequence tags (ESTs) from 10 cDNA libraries have been sequenced, of which almost 5000 non-redundant tags have been submitted to the EMBL data bank. The quality of the cDNA libraries used is analysed. Similarity searches in international protein data banks have allowed the detection of significant similarities to a(More)
A polyubiquitin-encoding gene was identified from a Nicotiana tabacum genomic library using a specific probe spanning the 3' untranslated region of the corresponding cDNA. The gene, Ubi.U4, is expressed in various amounts in the whole plant, except in just-fully-expanded leaves. Genomic blots indicate that it originates from N. tomentosiformis. Sequence(More)
We have previously shown by RNA gel blot analyses that the tobacco polyubiquitin-encoding gene Ubi.U4 is expressed in a complex pattern during plant development (Genschik et al., 1994). In order to study its tissue-specific expression, we cloned the fragment containing the −263 bp proximal promoter of the gene, the leader intron and the first ubiquitin(More)
It is widely assumed that mitotic cyclins are rapidly degraded during anaphase, leading to the inactivation of the cell cycle–dependent protein kinase Cdc2 and allowing exit from mitosis. The proteolysis of mitotic cyclins is ubiquitin/26S proteasome mediated and requires the presence of the destruction box motif at the N terminus of the proteins. As a(More)
Transformation of a mesophyll cell into a viable protoplast that is able to re-enter the cell cycle, divide and further differentiate into organs, is accompanied by a very rapid and important increase in ubiquitin gene expression. Three major size classes of ubiquitin mRNA transcripts were observed in protoplasts as soon as they were isolated and incubated(More)
A genomic clone (Ext 1.4) encoding an extensin was isolated from a Nicotiana tabacum genomic library. The encoded polypeptide showed features characteristic of extensins such as Ser-(Pro)4 repeats and a high content in Tyr and Lys residues. The presence of one Tyr-Leu-Tyr-Lys motif suggests the possibility for one intramolecular isodityrosine cross-link(More)
Proteasomes are the essential components of complexes involved in an extralysosomal energy- and ubiquitin-dependent proteolytic pathway. The first alpha-type proteasome subunit in plants has recently been described. In this work, the sequence of the first beta-type proteasome subunit in plants, isolated from Arabidopsis thaliana cDNA libraries is reported.(More)
A cDNA library from freshly isolated protoplasts was differentially screened using cDNAs from mesophyll cells, stressed leaf strips and cell suspension cultures. One of the selected clones, 6P229, turned out to encode a putative polypeptide showing homology to the btuE periplasmic protein of Escherichia coli and to animal selenium-dependent glutathione(More)
To decipher the early events preceding the re-entry of somatic cells into the cell cycle, we constructed a cDNA library from 6-h-old protoplasts of Nicotiana sylvestris. We characterized three mRNAs, via their cDNAs, that accumulate at very high levels 6 h after the beginning of the culture. Two of them could be identified by comparison of the deduced amino(More)