The C-terminal tails of SMS1 are important for homodimeric interactions.
A–D, COS7 cells were transfected with a plasmid encoding FLAG- or V5-tagged SMS1-WT, SMS1-ΔN68, SMS1-ΔC22, or SMS1-ΔN68C22 as indicated. A and C, left, cell lysates; right, immunoprecipitates (anti-FLAG beads). IB, immunoblot; IP, immunoprecipitation. B and D, the quantities of V5-tagged SMS1 precipitated with FLAG-tagged SMS1 are represented as the ratios of the band intensities. Results are from one experiment representative of at least three independent experiments. Individual data points are shown as a scatterplot. Values represent the mean ± S.D. from at least three independent experiments. *, p < 0.01; **, p < 0.05. E, the interaction between the C-terminal tails in SMS1, shown as a thin arrow line, is not primarily responsible for the formation of the SMS1 homodimer. The bold arrow line shows the interaction between the C-terminal tail and another, unidentified region in SMS1 (U in the box), which seems to be primarily responsible for the formation of the SMS1 homodimer.