Once reduced, the metal is likely transported into the enterocyte by copper transporter 1 (CTR1) . The precise mechanism of this transport process is not currently clear, as intestine-specific knockout of CTR1 leads to increased enterocyte Cu levels, with the Cu being apparently trapped in an intracellular compartment where it is not biologically available . The transport
of Cu(II) across the apical brush border membrane involves both a non-energy-dependent saturable carrier, and diffusion .