FIGURE 2.

Biosynthetic and in vitro glucuronylation activities of the two isoforms of rat GlcAT-P. A, the two isoforms of GlcAT-P (lGlcAT-P and sGlcAT-P) differ in only the additional 13 amino acids (P-N13) in the N-terminal cytoplasmic tail. B, Neuro2A cells were transfected with the lGlcAT-P or sGlcAT-P expression plasmid or the empty vector (mock). Cells were lysed and treated with or without PNGase F and then subjected to Western blotting with M6749 mAb (left), GP2 (anti-GlcAT-P catalytic region) pAb (top right), or anti-P-N13 pAb (lower right). C, in vitro glucuronyltransferase activity toward a glycoprotein acceptor, asialo-orosomucoid, was measured. Mock treated-, lGlcAT-P-expressing, or sGlcAT-P-expressing Neuro2A cells were lysed and used as an enzyme source. The enzyme source solution was also subjected to Western blotting with M6749 mAb or GP2 pAb (right).