He is known for his pioneering work in the field of protein modifications by ubiquitin and ubiquitin-like modifiers.
He then completed his Ph.D. at the Max Planck Institute for Molecular Genetics in Berlin in 1983.
After his Ph.D., he joined the laboratory of Alexander Varshavsky at the Massachusetts Institute of Technology.
In 1988 he returned to Germany, becoming a junior group leader at the Friedrich Miescher Laboratory of the Max Planck Society in Tübingen in 1988 and then professor at the Center of Molecular Biology (ZMBH), University of Heidelberg in 1993.
From 1998 until his death he was a director of the Department of Molecular Cell Biology, the Max Planck Institute of Biochemistry in Martinsried.