TRIM1 is a new LRRK2 E3 ubiquitin ligase. (a) Diagram of LRRK2 protein domains (ARM, armadillo repeat; ANK, ankyrin repeat; LRR, leucine-rich repeat; ROC, ras of complex proteins; COR, C-terminal of ROC domain). (b) Schematic of LRRK2 interactome in HEK-293T cells. LRRK2 interacting partners are classified radially according to function (aqua, new LRRK2 interacting partners; white, previously identified LRRK2 partners; size of circle indicates fold-change over empty vector control; circles without solid black outline had no peptides present in empty vector control; arrow indicates TRIM1). FLAG-LRRK2 was immunoprecipitated and interacting partners were identified and quantified by MS. Data represent at least four total independent replicates from two experiments and are additionally shown in Table S1. (c) Diagram of TRIM1 protein domains (FNIII, fibronectin III domain). (d) Coimmunoprecipitation of myc-TRIM1 with FLAG-LRRK2 in HEK-293T cells. (e) Coimmunoprecipitation of endogenous LRRK2 with TRIM1 in WT HEK-293T and HEK-293T TRIM1 CRISPR KO line. From left to right: WT HEK-293T cells transfected with exogenous FLAG-LRRK2 (positive control), WT HEK-293T cells, TRIM1 KO HEK-293T cells, and WT HEK-293T cells treated with 500 nM MLi-2 for 5 h. Low exp, short exposure of membrane; high exp, longer exposure of membrane. (f) Coimmunoprecipitation and ubiquitination of FLAG-LRRK2 with myc-TRIM1 or myc-CHIP in the presence of HA-ubiquitin in HEK-293T cells. Source data are available for this figure: SourceData F1.