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Human mitochondrial NAD(P) + -dependent malic enzyme (m-NAD-ME) is a malic enzyme isoform with dual cofactor specificity, ATP inhibition and substrate cooperativity. The determinant of ATP inhibition in malic enzyme isoforms has not yet been identified. | ỊFEBS Journal Different roles of two c-tubulin isotypes in the cytoskeleton of the Antarctic ciliate Euplotes focardii Remodelling of interaction surfaces may enhance microtubule nucleation at low temperature Franrocna a 1-71 a Io1 Qa nd ra Pl ir r i a rol 111 Pa rĨTỈa Rallarini1 Ronalrl l lall j2 Ạ I r I Itiih3 rial lUcoUa IVI aiziaie ual lUia I ucciaieiii I anizia Daiiaiii II HUI Idiu ivieiM M pcMJZUH Valentin A. Ilyin3 H. W. Detrich III3 and Cristina Miceli1 1 Dipartimento di Biologia Molecolare Cellulare e Animale University of Camerino Italy 2 Laboratoire d Enzymologie et Biochimie Structurales Centre Nationalde la Recherche Scientifique Gif-sur-Yvette France 3 Department of Biology Northeastern University Boston MA USA Keywords microtubule nucleation molecular coldadaptation psychrophilic microorganism quantitative PCR tubulin genes Correspondence C. Miceli Dipartimento di Biologia Molecolare Cellulare e Animale University of Camerino Via Gentile III da Varano 62032 Camerino MC Italy Fax 39 0737 40 32 90 Tel 39 0737 40 32 55 E-mail cristina.miceli@unicam.it Received 22 July 2008 revised 27 August 2008 accepted 4 September 2008 doi 10.1111 j.1742-4658.2008.06666.x y-Tubulin belongs to the tubulin superfamily and plays an essential role in the nucleation of cellular microtubules. In the present study we report the characterization of y-tubulin from the psychrophilic Antarctic ciliate Eupl-otes focardii. In this organism y-tubulin is encoded by two genes y-T1 and y-T2 that produce distinct isotypes. Comparison of the y-T1 and y-T2 primary sequences to a Euplotes y-tubulin consensus derived from mesophilic i.e. temperate congeneric species revealed the presence of numerous unique amino acid substitutions particularly in y-T2. Structural models of y-T1 and y-T2 obtained using the 3D structure of human y-tubulin as a template suggest that these substitutions are responsible for conformational and or polarity differences located a in the regions involved in .
