Identification and comparisons of selenoproteins in rat brain and mouse neuroblastoma cells

Male weanling rats, fed a Se-deficient torula-yeast diet or Se-adequate diet for 5 weeks, were injected with 400 {mu}Ci of {sup 75}Se as selenite, and sacrificed 2 and 4 wk after injection. Selenoproteins identified by SDS-PAGE included 6 major {sup 75}Se-peaks in cortex and cerebellum. While Se deficiency increased {sup 75}Se labeling of brain proteins, the percentages in each of the 6 peaks were unaffected by Se status. The total Se content of deficient cortex was only 5-10% less than adequate cortex, while deficient liver Se was 25-fold lower than adequate liver. The same 6 {sup 75}Se-peaks were identified in liver, with the 23-kDa peak greatly increased in Se adequate liver. When the 23-kDa peak was excluded, the relative distribution of {sup 75}Se in the remaining peaks was similar for liver, cortex, and cerebellum. Mouse neuroblastoma cells grown with {sup 75}Se-selenite showed labeling of 6 proteins of similar molecular weight as rat cortex, but {sup 75}Se distribution was different. Overall, the liver 23-kDa protein appeared to be the only {sup 75}Se-peak greatly changed as a result of Se status.