Required for high affinity copper (probably reduced Cu I) transport into the cell. Oligomer. Expressed in limited copper conditions. Expression is positively controlled by MAC1 and TYE7. Induced during biofilm formation and contact with macrophages as well as by alkaline pH via RIM101. Expression is down-regulated by 17-beta-estradiol. Impairs growth on solid low-copper and low-iron medium and displays altered morphology in response to copper-depleted conditions.