FIGURE 7.

Trx/TrxR drives VKOR-supported carboxylation. Intact washed microsomes were prepared from insect cells infected with baculovirus containing carboxylase (Carb) or coinfected with baculoviruses containing carboxylase and VKOR (VKOR·Carb). The microsomes were then assayed in a carboxylation reaction using the indicated reductants and either vitamin K epoxide (KO) (a) or vitamin K quinone (K) (b). The details of the assay are described under “Experimental Procedures.” The lack of activity in the carboxylase samples was not due to low carboxylase levels, as Western analysis and detection by LiCor showed that carboxylase expression was actually 2-fold higher in the “Carb” microsomes than in the “VKOR·Carb” microsomes (data not shown).