Structure and function analysis of Mcb1. A, a schematic of Mcb1 truncations (1–10) made with a summary of their toxicity to wild-type cells, complementation of Δmcb1, and interaction with Mcm4. B, wild-type cells (FY254) transformed with plasmids encoding Mcb1 truncations (1–10) were streaked on EMM-leucine plates with (+T; left) or without (−T; right) thiamine to repress or induce nmt1 promoter, respectively. aa, amino acids; ND, not determined.