Myoblast city

Myoblast city (Mbc) is a guanine nucleotide exchange factor (GEF)–like protein in the fruit fly Drosophila melanogaster and is the ortholog of the mammalian Dock180 protein. Mbc activates the small GTPase Rac1 to regulate actin cytoskeleton remodeling during development. The gene was first identified through deletion mapping on the right arm of chromosome 3, where multiple lethal recessive alleles revealed its essential developmental role. Mbc is required for several morphogenetic processes, including myoblast fusion, dorsal closure, and axon guidance, and embryos lacking functional Mbc display severe defects in muscle formation and epithelial morphogenesis. Mutated mbc embryos exhibit defects particularly in dorsal closure, cytoskeletal organization, myogenesis, and neural development.