We selected GABARAPL2endoHA cells for a proof-of-principle immunoprecipitation (IP) followed by mass spectrometric (MS) analysis to identify new binding partner candidates of a hATG8 family member at endogenous levels. To distinguish between candidates that bind preferentially to PE-conjugated versus unconjugated GABARAPL2 we treated stable isotope labeling with amino acids in cell culture (SILAC)-labeled GABARAPL2endoHA cells with Torin1 and BafA1 (light) or ATG7 inhibitor (heavy).