STRUCTURAL AND FUNCTIONAL ANALYSIS OF DROSOPHILA MYOSIN V

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Drosophila myosin V has a strikingly different motor mechanism from that of vertebrate myosin Va and it is a non-processive, ensemble motor. We have independently generated two polyclonal antibody against myosin V. One polyclonal antibody was generated against the coil-coiled domain of myosin V and another polyclonal against the tail end of myosin V. Immunostaining of the Drosophila larval salivary gland localized both antibodies to the nuclear envelope. It colocalized with Drosophila lamin C, a marker for the inner membrane of the larval nuclear envelope. Immunoprecipitation experiments of larval extracts using lamin C antibody pulled down myosin V. Mutants of myosin V and over expression of myosin V in the larval salivary gland using the UAS-GAL4 system showed aberrant lamin C staining on the nuclear envelope. Immunoprecipitation experiments using myosin V antibody pulled down Rab 5 protein. Rab 5 is a small GTPase which has been shown to localize to the early endosomes. Immunostaining using Rab 5 antibody in the larval salivary gland showed staining in the nuclear envelope, similar to the staining of lamin C and myosin V. In order to determine if the localization of myosin V and Rab 5 is in the inner or outer membrane of the larval nuclear envelope, we are performing immunogold electron microscopy experiments. We postulate that Drosophila myosin V, Rab 5 and lamin C are interacting with each other to maintain the structural integrity of the nuclear envelope of the larval salivary gland.