Walter Gilbert and Benno Müller-Hill were the first to successfully identify it, using a different technique. However, Arthur Riggs was the first to purify usable quantities of a transcription factor protein, the lac repressor.
Walter Gilbert and Benno Müller-Hill were among the first to identify it using an alternative technique. Conversely, Arthur Riggs was the first to isolate sufficient quantities of a transcription factor protein, which is the lac repressor.