Chaperone and import receptor for newly-synthesized class I PMPs; binds peroxisomal membrane proteins (PMPs) in the cytoplasm and delivers them to the peroxisome for subsequent insertion into the peroxisomal membrane; interacts with the phosphorylated loop region of the peroxisomal membrane anchor Pex3p, where it physically interacts with the cargo-binding domain of the myosin V motor protein Myo2p and contributes to peroxisome partitioning