Fig. 6. The role of -tubulin in early maturation. Maturation of centrioles occurs at G2/M. Old centrioles are shown in red and young centrioles are shown in blue. Old centrioles are morphologically identifiable by the presence of subdistal appendages. Maturation of basal bodies is hypothesized to occur at two time points in the cell cycle: early maturation occurs at the end of mitosis and a later maturation event takes palce at G2/M. Young basal bodies that show early maturation are shown in purple. Old basal bodies are shown in red. Young basal bodies that have not matured are shown in blue. The hypothesis suggests that early maturation fails in uni3-1 cells as indicated by the lack of purple basal bodies. tua2 Mutations restore early maturation as indicated by the appearance of purple basal bodies.