In his own laboratory, Tjian researches the biochemical steps that control how genes are turned on and off, steps that are key to the process of decoding the human genome. He discovered proteins called transcription factors that bind to specific sites in DNA and play a critical role in controlling how genetic information is transcribed and translated into the thousands of biomolecules that control the growth and development of cells, tissues, and organisms. Tjian's laboratory has illuminated the relationship between disruptions in the process of transcription and human diseases such as cancer, diabetes, and Huntington's disease. More recently, he has begun studying how transcription factors control the differentiation of embryonic stem cells into muscle, liver, and neurons. His most recent interest is in the development of new approaches to image biochemical activities in living cells.
Tjian was born in Hong Kong, the youngest of nine children. His family fled China before the Communist Revolution and eventually settled in New Jersey. Known as a voracious consumer of scientific information and data, Tjian famously talked his way into the biochemistry laboratory of the late Daniel Koshland (the 2000 Seaborg medalist) as a Berkeley undergraduate—even though he had not yet taken a single biochemistry course.
Tjian went on to receive a bachelor's degree in biochemistry from Berkeley in 1971 and a Ph.D. from Harvard University in 1976. After completing a postdoctoral fellowship at the Cold Spring Harbor Laboratory with James Watson, he joined the Berkeley faculty in 1979. At Berkeley, Tjian assumed a variety of leadership roles, including spearheading a major campus initiative to support and implement new paradigms for bioscience teaching and research. He is a member of the National Academy of Sciences and has received many awards honoring his scientific contributions, including the Alfred P. Sloan Prize from the General Motors Cancer Research Foundation and the Louisa Gross Horwitz Prize from Columbia University. He was named California Scientist of the Year in 1994.
Tjian and his wife Claudia, an attorney, have two daughters, Alexis (a 1997 UCLA graduate) and Lindsey.