Observation of Ctf19 Phosphorylation In Vivo
(A) Ctf19-3FLAG, purified from exponentially growing cells expressing either wild-type CTF19 (SMH372) or ctf19-9A (SMH378) was resolved on a phostag gel and detected by western blot (arrow, phosphorylated Ctf19; ∗, non-specific band).
(B) Ctf19 phosphorylation was assessed as in (A) for strains expressing CTF19, ctf19-9A, ctf19-2A, or ctf19-3A-2 (SMH372, SMH378, SMH449, and SMH450, respectively).
(C) Ctf19 phosphorylation assessed as in (A) for strains expressing CTF19, ctf19-9A, or CTF19 in a chl4Δ background (SMH372, SMH378, and SMH401, respectively). Cells were untreated or arrested in G1 as indicated (arrows, phosphorylated Ctf19; ∗, non-specific band).
(D) Strains bearing Ctf19-3FLAG and an inducible DDK expression cassette (Cdc7-6His, Dbf4 untagged) were not induced (left) or induced to express DDK (right) for 2 hr. Ctf19 phosphorylation was assessed in strains lacking CHL4 (SMH429) or expressing ctf19-9A (SMH430).