An evolutionary route chart of the YidC/Oxa/Alb3 family in the three domains of life (for detailed illustration please see the text). In cells, chloroplast is represented by polygon and mitochondrion by ellipse. Degenerated mitochondrion and plastid are represented by dashed polygon and dashed ellipse, respectively. Asterisks (*) indicate the Oxa2 possessing an additional C-terminal TPR domain in green algae and plants. Dashed line indicates an uncertain relationship. The color of the letters refers to their evolutionary correlations of the members of the family.