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In an effort to shed more light on the early evolutionary history of the heavy-chain subunits of heteromeric amino acid transporters (hcHATs) rBAT and 4F2hc within the a-amylase family GH13, a bioinformatics study was undertaken. | ỊFEBS Journal Looking for the ancestry of the heavy-chain subunits of heteromeric amino acid transporters rBAT and 4F2hc within the GH13 a-amylase family Marek Gabrisko1 and Stefan Janecek1 2 1 Institute of Molecular Biology Slovak Academy of Sciences Bratislava Slovakia 2 Department of Biotechnology Faculty of NaturalSciences University of SS. Cyriland Methodius Trnava Slovakia Keywords 4F2hc evolutionary relatedness oligo-1 6-glucosidase subfamily rBAT a-amylase family Correspondence S. Janecek Institute of Molecular Biology Slovak Academy of Sciences Dubravska cesta 21 SK-84551 Bratislava Slovakia Fax 421 2 59307416 Tel 421 2 59307420 E-mail Stefan.Janecek@savba.sk Received 15 July 2009 revised 18 September 2009 accepted 12 October 2009 doi 10.1111 j.1742-4658.2009.07434.x In an effort to shed more light on the early evolutionary history of the heavy-chain subunits of heteromeric amino acid transporters hcHATs rBAT and 4F2hc within the a-amylase family GH13 a bioinformatics study was undertaken. The focus of the study was on a detailed sequence comparison of rBAT and 4F2hc proteins from as wide as possible taxonomic spectrum and enzyme specificities from the a-amylase family. The GH13 enzymes were selected from the so-called GH13 oligo-1 6-glucosidase and neopullulanase subfamilies that represent the a-amylase family enzyme groups most closely related to hcHATs. Within this study more than 30 hcHAT-like proteins designated here as hcHAT1 and hcHAT2 groups were identified in basal Metazoa. Of the GH13 catalytic triad only the catalytic nucleophile aspartic acid 199 of the oligo-1 6-glucosidase could have its counterpart in some 4F2hc proteins whereas most rBATs contain the correspondences for the entire GH13 catalytic triad. Moreover the 4F2hc proteins lack not only domain B typical for GH13 enzymes but also a stretch of 40 amino acid residues succeeding the b4-strand of the catalytic TIM barrel. rBATs have the entire domain B as well as longer loop 4. The higher
