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. 1999 Aug 31;96(18):10176–10181. doi: 10.1073/pnas.96.18.10176

Figure 4.

Figure 4

Modulation of the actin-bundling activity of T-plastin by SipA. The bundling activity T-plastin at various concentrations alone (A) or in the presence of SipA (1.5 μM) (B) or SopE (1.5 μM) (as negative control) (C) was examined by using a low-speed cosedimentation assay. The concentration of T-plastin ranged from 1 μM (lane 1) to 0.0625 μM (lane 5) in a series of 1:2 dilutions. The presence of actin in supernatants (S) or pellets (P) of the cosedimentation assay was determined by Coomassie blue staining. The quantitation of the experiments in A–C is presented in D and is expressed as % of the total amount of actin in the reaction that is present in the pellet fraction. (E) Calcium dependence of the actin-bundling activity of T-plastin in the presence of SipA. The actin-bundling activity of T-plastin (0.25 μM) in the presence of SipA (3 μM) was examined by using a low-speed cosedimentation assay as described above. The concentration of calcium ranged from 1 mM (lane 1) to 0.03125 mM (lane 6) in a series of 1:2 dilutions. Samples in lanes 6 of A–C and lane 7 in E represent bundling reactions in the absence of T-plastin and calcium respectively. Equivalent results were obtained in three repetitions of this experiment.