PP1 is a conserved eukaryotic serine/threonine phosphatase that regulates many aspects of
mitosis and meiosis, often working in concert with other phosphatases, such as CDC14 and
CDC25. The proliferative stages of the malaria parasite life cycle include sexual development
within the mosquito vector, with male gamete formation characterized by an atypical rapid
mitosis, consisting of three rounds of DNA synthesis, successive spindle formation with
clustered kinetochores, and a meiotic stage during zygote to ookinete development following
fertilization. It is unclear how PP1 is involved in these unusual processes. Using real-time livecell and ultrastructural imaging, conditional gene knockdown, RNA-seq and proteomic
approaches, we show that Plasmodium PP1 is implicated in both mitotic exit and, potentially,
establishing cell polarity during zygote development in the mosquito midgut, suggesting that
small molecule inhibitors of PP1 should be explored for blocking parasite transmission