CuPP, periplasmic copper bound to chaperones, and CuCyt, cytoplasmic copper bound to chaperones. PPCP, periplasmic and outer membrane proteins; CytCP cytoplasmic and inner membrane proteins. Black arrows represent transport and binding, blue arrows represent synthesis and degradation of PPCP and red dashed arrow represents induction of PPCP synthesis by CuCyt. Note that synthesis of PPCP happens in the cytoplasm and the protein is appropriately transported to the periplasm, but for clarity the synthesis arrow is included in the periplasm in this diagram.