Cloning, expression and functional characterization of rat napsin.

A full-length cDNA clone coding for rat napsin was identified by homology search of the ZooSeq rat EST database (Incyte). Northern blot analysis revealed high expression of napsin mRNA transcripts in kidney, lung and spleen. Western blot analysis showed that rat napsin is expressed in kidney as a 50-kDa, highly glycosylated, monomeric protein. Lysates prepared from human embryonic kidney cells (HEK293) transfected with rat napsin showed increased enzymatic activity which was inhibited by pepstatin.