Keiji Tanaka was born in 1949 and started his research career in 1972 with studies on the amino acid and protein metabolism in the Institute of Enzyme Research, after graduating from the Faculty of Medicine (School of Nutrition) at The University of Tokushima. He received his Ph.D. from The University of Tokushima in 1980, working on the hepatic protein metabolism. He was promoted to an assistant professor in 1976 and an associate professor in 1995 at the Institute for Enzyme Research at The University of Tokushima, and a head of the Department of Molecular Oncology in 1996, a vice-director in 2002, and an acting director in 2006 at The Tokyo Metropolitan Institute of Medical Science. Currently, he is a director general at Tokyo Metropolitan Institute of Medical Science since 2011. He was a postdoctoral fellow at Harvard Medical School, USA (1981-1983). At present he is a guest professor of Ochanomizu Woman’s University, Tokyo Medical and Dental University, The University of Tokyo Graduate School of Frontier Sciences, Juntendo University School of Medicine, Niigata University School of Medicine, and Tukuba University School of Medicine. Over the past 25 years, he focused on elucidating the structure and molecular/physiological functions of the proteasome. The discoveries of proteasomes in1988, immunoproteasomes in 1994, hybrid proteasomes in 2000, and thymoproteasomes in 2007 are the highlights of his study. His current research interests include intracellular proteolysis mediated by the proteasome, ubiquitin, and autophagy system in eukaryotes in general. He is the author of over 350 papers in refereed journals. He was awarded the Naito Memorial Foundation Prize in 2003, the Asahi Prize, the Uehara Prize in 2004, the Toray Science Technology Prize in 2007, the Takeda Prize for Medical Science in 2009, the Japan Academy Prize in 2010, and the Keio Prize for Medical Science, 2011. He is an editorial board member of Molecular Cell since 2006 and Cell since 2009. He is the recipient of funds from The Specially Promoted Research of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) and The Target Protein Project of MEXT of Japan.