Using the RUSH (Retention Using Selective Hooks) method to study the secretion process of ACE2 from the endoplasmic reticulum to the plasma membrane, we transfected plasmids into cells and initiated secretion with biotin. ACE2 was released from the endoplasmic reticulum to the plasma membrane. We collected samples every 5 minutes within a 45-minute period, using cells without plasmid transfection as a control. We then employed Flag pull-down assays followed by mass spectrometry to identify the interacting proteins of ACE2 during this process.