LRRK2 Phosphorylation.

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene were discovered in 2004 and have been found to be the most frequently mutated gene in Parkinson's disease. LRRK2 is a large multi-domain protein with a functional GTPase and kinase domain. The signal transduction pathways in which LRRK2 is dysfunctional in the disease state are only now being resolved, but we do know that LRRK2 is, itself, a substrate of multiple kinases and phosphatases and exists in variable phosphorylated states. Autophosphorylation of LRRK2 can impact GTPase and pathological outcomes. LRRK2 serines (910/935/955/973) are differentially phosphorylated in pathogenic PD mutations and after LRRK2 kinase inhibition. The phosphorylation status of LRRK2 can therefore provide key insight into the mechanisms of kinase dysfunction during disease. This chapter will describe the identification of LRRK2 phosphorylation sites and how phosphoregulation of LRRK2 reveals its own kinase activity and regulates its ubiquitination and localization in vitro, in cells, and in tissues.