L-xylulose reductase (DCXR, also known as dicarbonyl/L-xylulose reductase) catalyzes the reversible NADPH dependent reduction of cytosolic L-xylulose to xylitol (Nakagawa et al. 2002). The enzyme is a tetramer (El Kabbani et al.2004) and may be associated with the plasma membrane (Boue et al. 1996). Mutations that inactivate DCXR are associated with essential pentosuria (Pierce et al. 2011; Wang & van Eys 1970).
Mutations that inactivate DCXR block the conversion of L-xylulose to xylitol. The two mutant alleles that have been characterized by DNA sequencing would encode truncated mRNAs and encode no detectable protein product. One of these mutant alleles, DCXR c.583?C, is annotated here (Pierce et al. 2011; Wang & van Eys 1970).