Browsing by Subject "Endosomal Sorting Complexes Required for Transport"

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    Cell division without FtsZ--a variety of redundant mechanisms.
    (Molecular microbiology, 2010-10) Erickson, Harold P; Osawa, Masaki
    Until 1998 it looked like all bacteria and archaea used a universal cytokinetic machine based on FtsZ. A dozen completely sequenced bacterial genomes all had an ftsZ gene, as did the several sequenced archaeal genomes. Then in 1998-1999 two species of Chlamydia were sequenced and found to have no ftsZ (Stephens et al., 1998; Kalman et al., 1999). Enthusiasts of FtsZ could hold out some hope for its primacy by thinking that these obligate parasites might use some host machinery for division. But the next year the genome of Aeropyrum pernix, a free living thermophilic archeon, was found to be without ftsZ (Kawarabayasi et al., 1999). Additional sequences suggested that the entire kingdom of Crenarchaea managed life and cell division without FtsZ. Among the bacteria the following are now known to have no ftsZ: the phylum Planctomycetes (Pilhofer et al., 2008), which is related to Chlamydiae but is free-living; Calyptogena okutanii (Kuwahara et al., 2007) and Carsonella ruddi (Nakabachi et al., 2006), both intracellular symbionts; Ureaplasma urealiticum (Glass et al., 2000) and Mycoplasma mobile (Jaffe et al., 2004). Since all of these prokaryotes divide, there must be mechanisms for cell division that are not based on FtsZ. © 2010 Blackwell Publishing Ltd.
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    The kinase Grk2 regulates Nedd4/Nedd4-2-dependent control of epithelial Na+ channels.
    (Proc Natl Acad Sci U S A, 2004-08-10) Dinudom, Anuwat; Fotia, Andrew B; Lefkowitz, Robert J; Young, John A; Kumar, Sharad; Cook, David I
    Epithelial Na(+) channels mediate the transport of Na across epithelia in the kidney, gut, and lungs and are required for blood pressure regulation. They are inhibited by ubiquitin protein ligases, such as Nedd4 and Nedd4-2, with loss of this inhibition leading to hypertension. Here, we report that these channels are maintained in the active state by the G protein-coupled receptor kinase, Grk2, which has been previously implicated in the development of essential hypertension. We also show that Grk2 phosphorylates the C terminus of the channel beta subunit and renders the channels insensitive to inhibition by Nedd4-2. This mechanism has not been previously reported to regulate epithelial Na(+) channels and provides a potential explanation for the observed association of Grk2 overactivity with hypertension. Here, we report a G protein-coupled receptor kinase regulating a membrane protein other than a receptor and provide a paradigm for understanding how the interaction between membrane proteins and ubiquitin protein ligases is controlled.