Peptides from prion proteins such as prion protein fragment, PrP[106-126], a 21 aa peptide, forms ion channels permeable to physiological ions. Channels form in planar lipid bilayers at concentrations greater than 20μM. Heterogeneous channels of various conductances are observed for a single peptide, perhaps reflecting different oligomeric states of the channel-forming peptide in the membrane.

PrP[106-126] is a protease resistant, neurotoxic, heterogeneous channel former. It may exist in at least two oligomeric β-sheet forms. One of its oligomeric forms is a Cu²⁺-sensitive fast-cation channel. It probably binds Cu²⁺ to M₁₀₉ and H₁₁₁ in the mouth of the channel (Kourie et al., 2003). The assembly of PrP into neurotoxic channels may underlie the toxicity associated with prion diseases.

The generalized transport reaction is:

ions (in) ions (out).