The LRRK2–Rab29 interaction is modulated by TRIM1’s E3 ligase activity. (a) Immunoblot of Rab29 phosphorylation with WT LRRK2 (top) or LRRK2-PD mutant R1441G (bottom) in the absence of overexpressed TRIM1 or with overexpression of myc-tagged WT TRIM1 (WT), microtubule-nonbinding TRIM1 (TRIM1 C), or TRIM1 lacking E3-ligase function (TRIM1∆RF). (b) Coimmunoprecipitation of Rab29 and TRIM1 variants with LRRK2 WT or R1441G. dox-ind., dox-induced. (c) Quantification of: Rab29 phosphorylation relative to total Rab29 in lysate from part A (top panel), Rab29 co-IPed with LRRK2 in the presence or absence of overexpressed TRIM1 variants from part B (middle panel) and Rab29 phosphorylation relative to total Rab29 in co-IP with LRRK2 in the presence or absence of overexpressed TRIM1 variants (bottom panel). All immunoblots are representative images, and quantification shows the mean value from at least three independent experiments, with error bars showing the SEM. Significance testing for panel c was performed using Kruskal–Wallis with post hoc Dunn test and Bonferroni correction. Source data are available for this figure: SourceData F8.