The results of magnetoresistance and magnetization measurements taken on a single crystal of PrBa2Cu3O7-delta are reported. Among the family of materials known as the 1-2-3 compounds, only Pr 1-2-3 exhibits non-metallic transport and is not superconducting. Our results suggest that hybridization of Pr orbitals with Cu-O valence states may be responsible for the nonmetallic transport properties of Pr 1-2-3.