Adding to nature’s repertoire

Out of thousands of possible kinds of amino acid, virtually all organisms use just 20 to build the proteins they need. Now, scientists have expanded this palette by coaxing some cells from mice to make proteins that include synthetic amino acids.

The researchers have already used the customized proteins to study basic cell biology, but the technique could someday make novel proteins for medicine or biotechnology, says study coleader Lei Wang of the Salk Institute for Biological Studies in La Jolla, Calif.