Figure 4. Inactivation of sphingolipid signaling confers resistance to iron toxicity.
A. Yeast sphingolipid-mediated signal transduction pathways. B. Strains were grown on normal minimal medium (SDC) or SDC containing 7mM FeCl3. C. Legends as in Fig. 1A. D. Immunoblot analysis of myc-tagged Ypk1p in normal and high iron conditions in wild-type cells or cells overexpressing Orm2p. SDS-PAGE was performed in the presence of 20 μM Phos-Tag. To demonstrate that the higher bands corresponded to phospho-Ypk1p, the extracts prepared from cells overexpressing Orm2p were treated with lambda (λ) phosphatase (right lane). E. Legends as in 4B.