Bicaudal-D, a Drosophila gene involved in developmental asymmetry: localized transcript accumulation in ovaries and sequence similarity to myosin heavy chain tail domains.

The Bicaudal-D (Bic-D) gene is essential for the differentiation of the oocyte in Drosophila. Dominant gain-of-function mutations result in the formation of double abdomen embryos. The Bic-D gene was cloned and identified using restriction fragment length polymorphisms, Northern analysis, and transformation rescue. Bic-D RNA accumulates in the oocyte during the earliest stages of oogenesis and is localized anteriorly in later stages. The predicted protein contains several extended amphipathic helices, and its similarity to myosin heavy chain tails, paramyosin, and kinesin suggests a similar type of coiled-coil protein interaction.