v-ATPase Vo and V1 domains were isolated via Co-IP from MEFs expressing HA-Atp6V1B2 and FLAG-Atp6VoaA3 using HA- and FLAG-tag antibodies. Treatment groups were full medium (control), amino acid starvation (60 min) and restimulation (30 min). Cells were grown in SILAC medium for 3 passages.