Aβ1 Aα1 Aβ2

rBAT-ED --DWWQEGPMYQIYPRSFKDSNKDGNGDLKGIQDKLDYITALNIKTVWITSFYKSSLKDF 173

2ZE0 KKTWWKEGVAYQIYPRSFMDANGDGIGDLRGIIEKLDYLVELGVDIVWICPIYRSPNADN 61

**:** ******** *:* ** ***:** :****:. *.:. *** .:*:*. *

Aα2 Aβ3 Bα1

rBAT-ED RYGVEDFREVDPIFGTMEDFENLVAAIHDKGLKLIIDFIPNHTSDKHIWFQLSRT-RTGK 232

2ZE0 GYDISDYYAIMDEFGTMDDFDELLAQAHRRGLKVILDLVINHTSDEHPWFIESRSSRDNP 121

*.:.*: : ****:**::*:* * :***:*:*:: *****:* ** **: .

Bα2 Bβ1 Bβ2

rBAT-ED YTDYYIWHDCTHENGKTIPPNNWLSVYGNSSWHFDEVRNQCYFHQFMKEQPDLNFRNPDV 292

2ZE0 KRDWYIWRDGKDG----REPNNWESIFGGSAWQYDERTGQYYLHIFDVKQPDLNWENSEV 177

*:***:* .. **** *::*.*:*::** .* *:* * :*****:.*.:*

Aα3 Aβ4 Aα4

rBAT-ED QEEIKEILRFWLTKGVDGFSLDAVKFLLEAKHLRDEI--QVNKTQIPDTVTQYSELYHDF 350

2ZE0 RQALYEMVNWWLDKGIDGFRIDAISHIKKKPGLPDLPLKYVPSFAGHMNQPGIMEYLREL 241

:: : *::.:** **:*** :**:..: : * * * . . . * :::

Aβ5 Aα5 Aβ6

rBAT-ED TTTQVGMHDIVRSFRQTMDQYSTEPGRYRFMGTEAYAESIDRTVMYYGLPFIQEADFPFN 410

2ZE0 KEQTFARY-DIMTVGEANG---VTVDEAEQWVGEE-NGVFNMIFQFEHLGL------287

. .. : : :. :: . . .. . * :: . : * :

Aα6 Aβ7 Aα7

rBAT-ED NYLSMLDTVSGNSVYEVITSWMENMPEGKWPNWMIGGPDSSRLTSRLGNQ------YVNV 464

2ZE0 --WERRASIDVRRLKRTLTKWQKGLENRGWNALFLENHDLPRSVSTWGNDRDYWAESAKA 344

. ::. . : ..:*.* :.: : * :: . * .* .* **: .:.

Aβ8

rBAT-ED MNMLLFTLPGTPITYYGEEIGMGNIVAANLNESYDINT------LRSKSPMQWDNSS 515

2ZE0 LGALYFFMQGTPFIYQGQEIGMTNVRFDDIRDYRDVSALRIIWKTGRDNSRTPMQWSGAS 424

:. * * : ***: * *:**** *: ::.: *:.: .*::****..:*

Aα8 Cβ1

rBAT-ED NAGFSEASNTWLPTNSDYHTVNVDVQKTQPRSALKLYQDLSLLHANELLLNRGWFCHLR- 574

2ZE0 NAGFTTG-TPWIKVNENYRTINVEAERRDPNSVWSFYRQMIQLRKANELFVYGTYDLLLE 483

****: . ..*: .*.:*:*:**:.:: :*.*. .:*::: *: : *: * : *

Cβ2 Cβ3 Cβ4 Cβ5 Cβ6

rBAT-ED NDSHYVVYTRELDGIDRIFIVVLNFGESTLLNLHNMISGLPA-KIRIRLSTNSADKGSKV 633

2ZE0 NHPSIYAYTRTLGRD-RALVVVNLSDRPSLYRYD---GFRLQSSDLALSNYPVR---PHK 536

*.. .*** *. * ::** ...:* ...... :

Cβ7 Cβ8

rBAT-ED DTSGIFLDKGEGLIFEHNTKNLLHRQTAFRDRCFVSNRACYSSVLNILYTSC 685

2ZE0 NATRFKLKPYEARVYIWKE------555

::: : *. *. :: :

Supplementary Figure 2. Structural alignment of human rBAT ectodomain (ED-rBAT) and GH13 a-glucosidase. This glucosidase is from the deep-sea bacterium Geobacillus sp. (PDBID: 2ZE0). This alignment has been obtained using MODELLER together with other homologous structures (PDBIDs: 2ZIC, 3GBD, 1UOK, 1M53 and 2DH2). The characteristic secondary structure elements are highlighted in the a-glucosidase sequence and labeled with the correspondent domain (A, B or C), a-helix (blue) or b-strand (green) and the order in the domain. The location of reported cystinuria missense mutations are highlighted in red in the ED-rBAT sequence, except for two mutations (Leu89Pro and Ile105Arg) that are in the TM segment. The last 33 rBAT residues are excluded from the structural alignment. *Identical residues in the aligned proteins. :Similar residues in the aligned proteins.