This item is intended only as supplementary material for the study of the metabolic processes of the methanolic yeast _Komagataella phaffii for the production of itaconic acid.For the preparation of proteome samples, strains were cultured in Delft minimal medium using methanol as the sole carbon source. Cultivation was carried out at 30°C and 220 rpm until reaching mid-log phase (OD600 = 2). Cells were then collected by centrifugation at 12,000 rpm and 4 °C for 30 s and rapidly quenched in liquid nitrogen.Strains that do not produce itaconic acid were used as controls.