Figure 4.

Evidence that Skb1 participates in the Ras1-dependent morphology control pathway in S. pombe. (A–E) Photomicrographs of a S. pombe ras1⁻ mutant, SPRN1, transformed with the control plasmids pAAUCM and pREP1 (A); pALR, which carries the wild-type ras1 gene (B); pAAUCMShk1, for overexpression of Shk1 (C); pREP1Skb1, for overexpression of Skb1 (D); and both pAAUCMShk1 and pREP1Skb1 (E). Overexpression of skb1 partially rescues the morphology defect of ras1-deleted cells. However, ras1⁻ cells overexpressing both Skb1 and Shk1 are substantially more elongate than cells overexpressing Skb1 or Shk1 alone. S. pombe transformants were patched onto EMM and grown overnight at 30°C prior to photomicroscopy.