LRRK2 gene mutations are a common cause of Parkinsons disease. The protein product of the gene has both kinase and GTPase activities. Because there are mutations in both kinase and GTPase domains, we consider that both activities are probably important for pathogenesis of Parkinsons disease. As such, we are trying to understand each activity in turn and how they interact. Ongoing work on this project is to map protein interactors particularly around the COR domain. We have some evidence now that there are functionally important co-chaperones that bind in this region. We have found that these interactions do allow the formation of a large protein complex that is stabilized by chaperones and has a novel function in autophagy. Mutations in the ROC and COR domains do affect this function but do not affect protein interactions. Ongoing work is aimed at understanding how the activities of LRRK2 impact complex function. We have also developed an approach to find novel modulators of LRRK2 function, initially via phosphorylation. We are currently trying to understand how this relates to cellular functions identified above.