The rough deal protein is a new kinetochore component required for accurate chromosome segregation in Drosophila

Mutations in the rough deal (rod) gene of Drosophila greatly increase the m issegregation of sister chromatids during mitosis, suggesting a role for th is gene product in spindle or kinetochore function. The activity provided b y rod also appears to be necessary for the recruitment of two known kinetoc hore components, Zw10 and cytoplasmic dynein, In this paper we describe the cloning of rough deal and an initial cytological characterization of its p roduct. The Rod protein shares no identifiable structural motif with other known proteins, although apparent homologs exist in the genomes of nematode and man. By immunocytochemistry we show that Rod displays a dynamic intrac ellular staining pattern, localizing first to kinetochores in prometaphase, but moving to kinetochore microtubules at metaphase, Early in anaphase the protein is once again restricted to the kinetochores, where it persists un til the end of telophase, This behavior is in all respects similar to that described for Zw10, and suggests that the proteins function together.