PLK3 and Parkinson disease: We chose these ratios to mirror the conditions observed in healthy individuals and PD patients, where typically only 4% of α‐Syn is phosphorylated in healthy individuals, whereas in Lewy bodies extracted from PD brains, over 90% of the α‐Syn is phosphorylated.[44] Phosphorylation of αSyn was performed using the kinase PLK3, which specifically phosphorylates αSyn at S129,[45] and was characterized using Western blot (Figure S12D, Supporting Information), and SiMPull analysis (Figure 6A,B).