Fig. (4) Only MCM protein without intein can be detected in Halobacterium cells. Western analysis of Halobacterium cell extract and recombinant MCM protein was performed as described in“Material and Methods”. Lane 1, cell extract (1 µg); lane 2, cell extract (0.5 µg); lane 3, purified MCM protein without intein (1ng); lane 4, purified full length MCM (20 ng). To the left are the positions of the molecular weight markers.