A new strategy for the prepn. of protein-functionalized polymer brushes is reported, which is based on a combination of surface-initiated atom transfer radical polymn. (ATRP), p-nitrophenyl chloroformate activation of the surface hydroxyl groups, and subsequent O6-benzylguanine (BG) functionalization. The BG-functionalized brushes are used to chemoselectively immobilize O6-alkylguanine-DNA-alkyltransferase (AGT) fusion proteins with a defined orientation and surface d. These protein-modified polymer brushes are attractive candidates for the development of protein microarrays. [on SciFinder (R)]