BioID Screen

BirA-Tpm3.1 was transfected into U2OS cells, which induced biotinylation of transverse arcs and ventral stress fibers (Supplementary Figure 1A). Backbone vector pmycBioID-C1 was transfected as control. Cells were grown for 24 h in complete DMEM and another 24 h in the presence of 50 μM biotin. Single-step affinity purifications of the biotinylated proteins, liquid chromatography mass spectrometry sample preparation, and mass spectrometry were performed as in Jiu et al. (2015). To obtain a list of high-confidence protein interactions for Tpm3.1 the data was filtered against our in-house BioID contaminant database.