Plays a role in apoptosis and consequently a role in imaginal disk patterning and growth. Expressed at low levels throughout the embryo. At later developmental stages, expressed in areas of high cell proliferation. From embryo stage 13, expression is high in central nervous system and midgut, especially in the gastric caeca. Expression also seen in larval imaginal disks and brain. Throughout development, from embryo to adult. Belongs to the selenophosphate synthase 1 family. Class II subfamily. The conserved active site Cys (or selenocysteine) residue in position 49 is replaced by an Arg and therefore lacks selenide-dependent monoselenophosphate synthetase activity.