Figure 2. High and low affinity copper uptake of copper and delivery to different enzymes and compartments.

At cellular copper levels, copper-uptake is known from S. cerevisiae and P. anserina to involve high affinity uptake mechanism. After reduction of copper mediated by a membrane located oxidoreductase (FRE) the import is performed by high affinity copper transporters (CTR). Expression of CTR-transporter genes is regulated transcriptionally by copper-dependent transcription factors. Intracellularly the copper is stored and distributed via copper binding chaperones and partially becomes transported into mitochondrion where it is stored and distributed to copper-containing proteins (i.e. cytochrome oxidase). Copper is also taken up by cells via a low copper-uptake system.