arco(endo)plasmic reticulum calcium ATPase (SERCA)2b maintains the cellular Ca 2+ homeostasis by transferring Ca 2+ from the cytosol to the lumen of the endoplasmic reticulum (ER). Recently, SERCA2b has also been shown to be involved in the biosynthesis of secreted and membrane proteins via direct protein–protein interactions, involving components of the ER folding and quality-control machinery, as well as newly synthesized G protein-coupled receptors.