TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The polypeptide has: one or more substitution corresponding to Val187Met/Gln/Cys/Gly/Tyr, Gln215Asp/Glu/Ser/Met/Leu/Cys/Phe/Ala, Ile218Trp, Ile222Gly/Tyr/Met/Pro/Ser/Trp, Tyr226Met/Thr/Pro/Gln, Met339Tyr/Glu/Asn, Gln342Asn/His/Arg/Cys/Phe/Gly/Ile/Lys/Leu/Pro/Ser/Thr/Trp, Asn346Gly/Ile, Tyr350Glu/Ser/Gln, Gly373Arg/Lys/Leu/Met/Tyr, Asn376Lys/Gln/Ala/Cys/Asp/Glu/Ile/Met/Pro, Ser383Tyr/Trp/Val/Cys/Glu/Ile/Leu/Gln/Arg, Phe446His/Asp/Ile, Thr448/Arg/Lys/His/Asp/Glu/Trp, T449F/His/Ala/Gly/Ile/Leu/Pro/Gln/Val, or Trp479Ser/Ile/Phe/Asp/Glu/His/Met/Asn/Arg/Thr/Tyr of SEQ ID NO: 59; or one or more substitution corresponding to Thr89Cys, Val187Met/Gln, Ala191Ile/Lys/Asp, Tyr214Leu/Pro, Gln215Asp/Glu/Ser, Ile218Trp, Ile222Gly/Tyr/Met, Tyr226Met/Thr, Gln338Arg/Ile, Met339Tyr, Gln341Val/Tyr/Ser, Gln342Asn/His/Arg, Leu343Tyr/Gln/Ile, Asn346Gly, Asn347Ser/Leu/Lys, Tyr350Glu, Gly373Arg, Asn376Lys/Gln, Thr380Tyr/Gly/Met, Ser383Tyr/Trp/Val, Phe446His/Asp, Thr448/Arg/Lys/His, Thr449Phe/His, Asn478Gln, or Trp479Ser/Ile/Phe of SEQ ID NO: 59; one or more of the substitutions corresponding to Val187Met/Gln, Gln215Asp/Glu/Ser, 1218Trp, Ile222GlyAla7Met, Tyr226Met/Thr, Met339Tyr, Gln342Asn/His/Arg, Asn346Gly, Tyr350Glu, Gly373Arg, Asn376Lys/Gln/, Ser383Tyr/Trp/Val, Phe446His/Asp, Thr448/Arg/Lys/His, Thr449Phe/His, or Trp479S/Ile/Phe of SEQ ID NO: 59; or one or more of the substitutions corresponding to Val187Met, Met339Tyr, Ile218Trp,Gln342Asn, Asn376Lys, Gly373Arg or Trp479Ser of SEQ ID NO: 59. The polypeptide has reduced glucose transport activity compared to the polypeptide of SEQ ID NO: 59 and increased xylose transport activity compared to the polypeptide of SEQ ID NO: 59. The polypeptide comprises amino acid sequences (Q) of formulae (Gly-Arg-x(3)-Gly-x(3)-Gly-x(11)-Glu-x(5)-(Leu-Ile-Val-Met)-Arg-Gly-x(12)-(Gly-Ala)), (Arg-x(14)-Gly-x(2)-Tyr-x(2)-(Tyr-Phe)-(Tyr-Phe)-(Gly-Ser-Ala-Leu)) and/or (Val-x(15)-(Gly-Asn-Arg)-(Arg-His)-Arg-x(2)-(Leu-Met)-x(2)-(Gly-Ala)), and a motif having sequences of formula (Gly-x(11)-Glu-x(5)(Leu-Ile-Val-Met)-Arg-Gly-x(12)-(Gly-Ala)). The fragments in (Q) correspond to the positions in SEQ ID NO: 59. The transformed host cell is yeast, and belongs to genus Saccharomyces, preferably Saccharomyces cerevisiae. The transformed host cell comprises a heterologuous nucleotide that encodes the polypeptide or encodes a polypeptide having substitution Phe85Ser/Val, Thr89Val/Leu, Val187Ile, Tyr226Ala, Gln338Asn, Met339Ser/Ala, Asn346Ala/Asp, Tyr350Ile, Glu373Asn/Ser, Asn376Ser, or Thr449Ser of sequence ID NO: 59 (where sequences not defined here may be found at ftp://ftp.wipo.int/pub/published_pct_sequences/publication). The polynucleotide encodes a polypeptide that is a mutant of a polypeptide, which that is native in the untransformed host cell. The polypeptide that is native in the untransformed host cell is a member of MFS transporters, a hexose transporter (Hxt) polypeptide, or a transporter polypeptide comprising galanin receptor 2, Hxt-1, Hxt-2, Hxt-3, Hxt-4, Hxt-5, Hxt-6, Hxt-7, Hxt-8, Hxt-9, Hxt-10, Hxt-11, Hxt-12, Hxt-13, Hxt-14, Hxt-15, Hxt-16 and Hxt-17. N.B. x is not defined.    TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preparation: No preparation method is given. EXAMPLE - No suitable example given.