Localization of Myosin 1b to Actin Protrusions Requires Phosphoinositide Binding

摘要: Myosin 1b (Myo1b), a class I myosin, is widely expressed, single-headed, actin-associated molecular motor. Transient kinetic and single-molecule studies indicate that it kinetically slow responds to tension. Localization subcellular fractionation Myo1b associates with the plasma membrane certain organelles such as endosomes lysosomes. Whether directly membranes unknown. We demonstrate here full-length rat binds specifically high affinity phosphatidylinositol 4,5-bisphosphate (PIP2) 3,4,5-triphosphate (PIP3), two phosphoinositides play important roles in cell signaling. Binding not Ca2+-dependent does involve calmodulin-binding IQ region neck domain of Myo1b. Furthermore, binding site contained entirely within C-terminal tail region, which contains putative pleckstrin homology domain. Single mutations abolish PIP2 PIP3 vitro. These same alter distribution Myc-tagged at protrusions HeLa cells where localizes. In addition, we found motor activity required for localization filopodia. results suggest plays an role vivo by regulating actin-enriched projections.