LRRK2 and Parkinson disease: Screening for binding partners has been a widely adopted strategy to narrow down the physiological activity of LRRK2.(Beilina et al., 2014; Manzoni et al., 2015) Given the genetic evidence implicating the ROC domain in PD pathogenesis, along with the general observation that GTPases often bind other proteins to either control their activity or to mediate cell signaling, we decided to focus on the mammalian LRRK2 ROC domain for identification of novel protein interactors of LRRK2.