This study investigates the structure and organization of a series of hybrid diblock copolymers based on poly(ethylene glycol) (PEG) and peptide sequences inspired by, the coiled coil protein folding motif. Circular dichroism spectroscopy and analytical untracentrifugation experiments indicate that the peptide sequences in these block copolymers act as structure-directing auxiliaries and mediate the formation of discrete nanosized assemblies. This self-assembly process is driven by the very, specific folding and organization properties of the peptide sequences and does not involve unspecific interactions leading to large polydisperse structures. The present study also demonstrates that the self-assembly properties of the hybrid block copolymers can be controlled via selective replacement of one or two amino acid residues in the peptide block. This is an attractive feature in view of possible biomedical applications. Preliminary biological experiments show that the properties of these polymers correlate with their self-assembly behavior.