Newly made proteins enter the ER (endoplasmic reticulum) and are first packaged into COPII-coated transport vesicles. These vesicles bud off from specific sites on the ER. The vesicles then fuse with the cis-Golgi network after tethering and SNARE-mediated fusion. The proteins then traverse the Golgi apparatus. Transport vesicles then depart from the trans-Golgi network. The proteins in these vesicles provide the new components for the cell’s plasma membrane and soluble proteins in the vesicles are secreted into the extracellular space.