We and others have previously observed a widespread expression of ORF1p in mouse and human neurons at steady-state. This somewhat surprising presence of ORF1p in neurons evokes the question of a possible physiological role of ORF1p specific to these cells. To address this question, we used a quantitative mass spectrometry approach to identify protein partners of endogenous ORF1p in mouse (differentiated MN9D) and human (differentiated LUHMES) dopaminergic neurons using well characterized and specific antibodies to ORF1p.