Puromycin is a well-known antibiotic that inhibits protein synthesis by competitive incorporation against an aminoacyl tRNA on the ribosome A site. Novel technology using this property of puromycin has been developed for convenient handling methods in protein research. Puromycin modified with another molecule is incorporated into a protein at the C-terminus, thus linking the desired molecule to the protein. Combination of in vitro translation with puromycin analogues has resulted in novel technologies such as display technology for screening, fluorescence labeling, affinity purification, and protein chip for proteomics.