Protein interaction partners of the exon 5,6-deleted AP1 mutant fused to GFP in the ap1-11 mutant background (AP1tet-GFP ap1-11), the site-directed mutagenized L154P and L168P AP1 mutant fused to GFP in the ap1-11 mutant background (AP1dm-GFP ap1-11), and the wild type AP1 fused to GFP in the ap1-11 mutant background (AP1-GFP ap1-11) were studied by GFP immunoprecipitation followed by mass spectrometry (IP-MS).