Roger Tsien

Roger Tsien shared the 2008 Nobel Prize in Chemistry with Martin Chalfie and Osamu Shimomura for the discovery and development of the green fluorescent protein (GFP). Tsien's specific contribution was engineering GFP into a palette of differently colored fluorescent proteins and making them practical tools for live-cell imaging.

Using directed mutagenesis, Tsien and his laboratory created variants of GFP that fluoresced in cyan, yellow, and blue, and they also developed red fluorescent proteins derived from coral species such as Discosoma. These multiple colors allowed researchers to label and track several different proteins simultaneously within the same living cell.

Tsien's laboratory developed numerous fluorescent protein variants including mCherry (a widely used red fluorescent protein), mPlum, and a range of genetically encoded calcium indicators such as the GCaMP family. These tools have become indispensable for neuroscientists studying brain activity and cell biologists tracking signaling dynamics in real time.

Tsien spent most of his career at the University of California, San Diego (UCSD), where he was a professor in the Department of Chemistry and Biochemistry and the Howard Hughes Medical Institute. He conducted his Nobel Prize-winning GFP engineering work at UCSD beginning in the 1990s.