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 th
at hybridization of Pr orbitals with Cu-O valence states may be respon
sible for the nonmetallic transport properties of Pr 1-2-3.