| Genetics News:
Tricellulin constitutes a novel barrier at tricellular contacts of epithelial cells.
Publication Date: 2005 Dec 19 PMID: 16365161Authors: Ikenouchi, J. - Furuse, M. - Furuse, K. - Sasaki, H. - Tsukita, S. - Tsukita, S.Journal: J Cell BiolFor epithelia to function as barriers, the intercellular space must be sealed. Sealing two adjacent cells at bicellular tight junctions (bTJs) is well described with the discovery of the claudins. Yet, there are still barrier weak points at tricellular contacts, where three cells join together. In this study, we identify tricellulin, the first integral membrane protein that is concentrated at the vertically oriented TJ strands of tricellular contacts. When tricellulin expression was suppressed with RNA interference, the epithelial barrier was compromised, and tricellular contacts and bTJs were disorganized. These findings indicate the critical function of tricellulin for formation of the epithelial barrier.
Site-specific biotinylation of RNA molecules by transcription using unnatural base pairs.
Publication Date: 2005 PMID: 16113238Authors: Moriyama, K. - Kimoto, M. - Mitsui, T. - Yokoyama, S. - Hirao, I.Journal: Nucleic Acids ResDirect site-specific biotinylation of RNA molecules was achieved by specific transcription mediated by unnatural base pairs. Unnatural base pairs between 2-amino-6-(2-thienyl)purine (denoted by s) and 2-oxo(1H)pyridine (denoted by y), or 2-amino-6-(2-thiazolyl)purine (denoted as v) and y specifically function in T7 transcription. Using these unnatural base pairs, the substrate of biotinylated-y (Bio-yTP) was selectively incorporated into RNA, opposite s or v in the DNA templates, by T7 RNA polymerase. This method was applied to the immobilization of an RNA aptamer on sensor chips, and the aptamer accurately recognized its target protein. This direct site-specific biotinylation will provide a tool for RNA-based biotechnologies.
Nucleotide analogues to investigate RNA structure and function.
Publication Date: 2005 Dec PMID: 16242990Authors: Das, S. R. - Fong, R. - Piccirilli, J. A.Journal: Curr Opin Chem BiolRNA plays an essential cellular role in nearly every aspect of the transmission and expression of genetic information, including regulatory roles that have significance for cellular development. Access to RNA bearing synthetic modifications has allowed biological chemists to probe deep into the inner workings of cellular processes. Here, we describe recent advances in harnessing the power of nucleotide analogues to obtain mechanistic and biological insights into RNA structure, function and dynamics.
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