Yasutomi Nishizuka, MJA, ForMemRS (西塚 泰美, Nishizuka Yasutomi, July 12, 1932 – November 4, 2004) [1] was a prominent Japanese biochemist and made important contributions to the understanding of molecular mechanism of signal transduction across the cell membrane.

[2] In 1977, he discovered protein kinase C, which plays significant roles in a variety of intracellular signal transduction processes.

After completing his studies in Japan, he spent one year as a postdoctoral fellow in Fritz Lipmann's laboratory at the Rockefeller University.

Nishizuka is well known for the construction of the fundamental concepts of the intracellular signal transduction cascade through his discovery of protein kinase C, also known as C kinase, and his analysis of its function, which revealed a new intracellular signal transduction system and elucidated the regulatory mechanisms involved in many biological phenomena, including cancer cell growth.

[4] He won the Wolf Prize in Medicine along with Michael J. Berridge of the University of Cambridge for "their discoveries concerning cellular transmembrane signalling involving phospholipids and calcium".