The present invention provides, among other things, methods and compositions for selective degradation of proteins. In some aspects, messenger RNAs (mRNAs) are described that encode a ubiquitin pathway moiety and a binding peptide that binds a target protein, wherein the mRNA is encapsulated within a lipid nanoparticle. Also provided herein are mRNAs that encode at least two binding peptides, wherein a first binding peptide binds a ubiquitin pathway moiety and a second binding peptide binds a target protein, and wherein the mRNA is encapsulated within a lipid nanoparticle.