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991.
Laure Ségurel Emma E. Thompson Timothée Flutre Jessica Lovstad Aarti Venkat Susan W. Margulis Jill Moyse Steve Ross Kathryn Gamble Guy Sella Carole Ober Molly Przeworski 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(45):18493-18498
The ABO histo-blood group, the critical determinant of transfusion incompatibility, was the first genetic polymorphism discovered in humans. Remarkably, ABO antigens are also polymorphic in many other primates, with the same two amino acid changes responsible for A and B specificity in all species sequenced to date. Whether this recurrence of A and B antigens is the result of an ancient polymorphism maintained across species or due to numerous, more recent instances of convergent evolution has been debated for decades, with a current consensus in support of convergent evolution. We show instead that genetic variation data in humans and gibbons as well as in Old World monkeys are inconsistent with a model of convergent evolution and support the hypothesis of an ancient, multiallelic polymorphism of which some alleles are shared by descent among species. These results demonstrate that the A and B blood groups result from a trans-species polymorphism among distantly related species and has remained under balancing selection for tens of millions of years—to date, the only such example in hominoids and Old World monkeys outside of the major histocompatibility complex. 相似文献
992.
Christos Pliotas Richard Ward Emma Branigan Akiko Rasmussen Gregor Hagelueken Hexian Huang Susan S. Black Ian R. Booth Olav Schiemann James H. Naismith 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(40):E2675-E2682
The heptameric mechanosensitive channel of small conductance (MscS) provides a critical function in Escherichia coli where it opens in response to increased bilayer tension. Three approaches have defined different closed and open structures of the channel, resulting in mutually incompatible models of gating. We have attached spin labels to cysteine mutants on key secondary structural elements specifically chosen to discriminate between the competing models. The resulting pulsed electron–electron double resonance (PELDOR) spectra matched predicted distance distributions for the open crystal structure of MscS. The fit for the predictions by structural models of MscS derived by other techniques was not convincing. The assignment of MscS as open in detergent by PELDOR was unexpected but is supported by two crystal structures of spin-labeled MscS. PELDOR is therefore shown to be a powerful experimental tool to interrogate the conformation of transmembrane regions of integral membrane proteins. 相似文献
993.
Selective inhibition of CD4+ T-cell cytokine production and autoimmunity by BET protein and c-Myc inhibitors 总被引:1,自引:0,他引:1
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Itamar Harel Yoshiro Maezawa Roi Avraham Ariel Rinon Hsiao-Yen Ma Joe W. Cross Noam Leviatan Julius Hegesh Achira Roy Jasmine Jacob-Hirsch Gideon Rechavi Jaime Carvajal Shubha Tole Chrissa Kioussi Susan Quaggin Eldad Tzahor 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(46):18839-18844
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