The University of Tokyo · Biochemistry, Genetics and Molecular Biology
Professor Shigeo Murata's research lab focuses on the molecular mechanisms of the ubiquitin-proteasome system, particularly the structure and function of proteasomes and their regulatory complexes in immune surveillance and cellular homeostasis. The lab investigates how specialized proteasome subunits, such as beta5t and PA28gamma, regulate peptide generation for antigen presentation in the immune system, with a strong emphasis on thymic selection and T cell development. Using genetically engineered mouse models, the lab explores the physiological roles of these proteasome components in health and disease. Their work bridges structural biology, immunology, and molecular genetics to uncover fundamental principles of intracellular protein degradation and immune recognition.
Figures are computed from collected data and may differ slightly.
Proteasomes are responsible for generating peptides presented by the class I major histocompatibility complex (MHC) molecules of the immune system. Here, we report the identification of a previously unrecognized catalytic subunit called beta5t. beta5t is expressed exclusively in cortical thymic epithelial cells, which are responsible for the positive selection of developing thymocytes. Although the chymotrypsin-like activity of proteasomes is considered to be important for the production of pept
The proteasome activator PA28 binds to both ends of the central catalytic machine, known as the 20 S proteasome, in opposite orientations to form the enzymatically active proteasome. The PA28 family is composed of three members designated alpha, beta, and gamma; PA28alpha and PA28beta form the heteropolymer mainly located in the cytoplasm, whereas PA28gamma forms a homopolymer that predominantly occurs in the nucleus. Available evidence indicates that the heteropolymer of PA28alpha and PA28beta
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