The murine "dilute" unconventional myosin (Myo5a) locus provides an outstanding genetic system to study molecular motor-cargo interactions and overlapping functions of closely related members of unconventional myosin families. Several aspects of the "dilute" system contribute to a powerful approach to answering these questions: the availability of multiple mutant alleles at the "dilute" locus and the "ashen," "leaden," and "dilute suppressor" loci; the recent characterization by Mercer of a second mammalian member of the "dilute" family, myr 6 (Myo5b); the ability to manipulate the genome of the mouse; and the availability of a primary melanocyte cell culture system that provides a visual assay for "dilute" myosin function. The studies will impact the organelle transport field by providing insights into motor-cargo interactions and testing for functional redundancy within an unconventional myosin family.
The studies have the following objectives:
1, Determine the functions of "dilute" and identify proteins that interact with "dilute" in both primary melanocyte and melanoma cell lines, using cell biological, biochemical, and genetic methods.
2, Identify regions of the "dilute" myosin tail that confer cargo-binding specificity using chimeric cDNA constructs with portions of the "dilute" myosin (myosin-Va) and its close relative, myr 6 (myosin-Vb), in both cultured cells and in transgenic mice.
