Figure 3.
Blocking phosphorylation of Mad3p abrogates the checkpoint arrest in response to lack of tension. Cultures of EK29 (GAL-SCC1 MAD3), EK26 (GAL-SCC1 mad3Δ), EK41 [GAL-SCC1 MAD3-2SA (S303A, S337A)], and EK43 [GAL-SCC1 MAD3-4SA (S10A, S303A, S337A, S486A)] expressing Pds1-myc18 were grown in the presence of galactose, synchronized with α-factor, and then released into glucose-containing medium to allow DNA replication in the absence of SCC1 expression. Lysates were prepared from samples taken at the times indicated and immunoblotted with anti-c-myc antibody to detect Pds1p.