Myosin 1c is a novel client for the UNC-45a chaperone. (A) Proximity-dependent BioID screen for UNC-45a interaction partners. Listed are the spectral count values of 10 of the most prominent, in vivo biotinylated proteins by BirA-tagged human UNC-45a in U2OS cells from two independent experiments. Myosin 1c is outlined in green. (Table S1 provides a complete list of in vivo biotinylated proteins by UNC-45a-BirA.) (B) WB analysis of myosin X and myosin 1c protein levels from three independent WT and UNC-45a knockout (KO) cell lysates. GAPDH was probed to demonstrate equal sample loading. (C) Presence of myosin 1c aggregates in WT and UNC-45a knockout cells expressing HA–myosin 1c construct 8 h after MG-132 administration. Fluorescent phalloidin, monoclonal anti–HA antibody, polyclonal antibody against NM-IIA heavy chain, and DAPI were applied to visualize F-actin, myosin 1c, NM-IIA, and nuclei, respectively. Red and yellow arrowheads indicate examples of HA–myosin 1c and NM-IIA containing aggregates, respectively, in UNC-45a knockout cells. Bars, 20 µm.