Catálogo de publicaciones - revistas

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>

<jats:title>Pre-Initiation Complex in 3D</jats:title> <jats:p> The regulation of gene expression is critical for almost every aspect of biology. Transcription—generating an RNA copy of a gene—requires the assembly of a large pre-initiation complex (PIC) at every RNA polymerase II (pol II) promoter. Roughly 32 proteins—the subunits of pol II and the general transcription factors—form a PIC that can recognize a minimal TATA-box promoter, select a transcription start site, and synthesize a nascent transcript. <jats:bold> Murakami <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.1238724">10.1126/science.1238724</jats:related-article> , published online 26 September; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6159" page="706" related-article-type="in-this-issue" vol="342" xlink:href="10.1126/science.1246170">Malik and Roeder</jats:related-article> </jats:bold> ) determined the three-dimensional map of the <jats:italic>Saccharomyces cerevisiae</jats:italic> 30-subunit PIC using cryo-electron microscopy. The saddle-shaped TATA binding protein, the boot-shaped transcription factor IIA (TFIIA), and promoter DNA ∼27 bp downstream of the TATA-box could all be seen. Cross-linking and mass spectrometry was used to determine the spatial proximity of the 30 subunits, revealing that the PIC forms two lobes with TFIIF forming a bridge between them. </jats:p>

<jats:title>From Here to There</jats:title> <jats:p> To form different tissues and organs, embryonic cells must migrate to new locations. Specific transcription factors, epigenetic and splicing programs, and microRNA regulatory networks regulate this process, which is known as the epithelial-to-mesenchymal transition (EMT). During EMT, considerable cellular plasticity is observed, and once activated at their new location, cells must again change into their new differentiated form. This “reverse” event is called the mesenchymal-to-epithelial transition (MET). <jats:bold>Nieto</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.1234850">10.1126/science.1234850</jats:related-article> ) reviews EMT and MET as observed during normal development and in the generation of cancer when cells leave the primary tumor and travel to other parts of the body forming metastases and secondary tumors. </jats:p>