Provided herein are methods and compositions relating to G protein-coupled receptor (GPCR) libraries having nucleic acids encoding for a scaffold comprising a GPCR binding domain. Libraries described herein include variegated libraries comprising nucleic acids each encoding for a predetermined variant of at least one predetermined reference nucleic acid sequence. Further described herein are protein libraries generated when the nucleic acid libraries are translated. Further described herein are cell libraries expressing variegated nucleic acid libraries described herein.
