Expression of rps9-Δ188. A) Sequence of the C terminus of S9A, S9B and the deleted protein rps9-Δ188. Lowercase letters indicate identical residues. B) Northern blot analysis of RNA samples prepared from the parental strain (wt), strain deleted of only RPS9A gene (ΔRPS9A), strain deleted of only the RPS9B gene (ΔRPS9B) and strain deleted of both genes and supplemented with a single-copy plasmid containing rps9-Δ188. The membrane was hybridized with probes recognizing RPS9 ORF (upper panel), RPL41 (middle panel) and 18S rRNA (lower panel). C) Western analysis of the sedimentation profile of rps9-Δ188. Cells expressing flag-tagged rps9-Δ188 were harvested and the cell extract was separated by velocity sedimentation on a sucrose gradient. The gradient was fractionated into 14 fractions and the proteins of each fraction were subjected to western analysis using anti-flag antibodies. The sedimentation positions of ribosomal complexes were derived from the OD254 profile of the gradient (not shown) and are indicated at the bottom of the panel.