S. Matsuda, H. Kosako, K. Takenaka, K. Moriyama, H. Sakai, T. Akiyama, Y. Gotoh, E. Nishida, "Xenopus MAP kinase activator: identification and function as a key intermediate in the phosphorylation cascade," The EMBO Journal, 11:973-82, 1992.
Eisuke Nishida (Department of Genetics and Molecular Biology, Institute for Virus Research, Kyoto University, Japan): "MAP kinases have been described as serine/threonine kinases that are activated commonly by various growth factors and tumor promoters in mammalian cultured cells. They are now thought to function as key molecules in a variety of signal transduction processes. As MAP kinases are unique in requiring both tyrosine and threonine phosphorylation to become active, it was hypothesized that two kinds of protein kinases, a serine/threonine kinase and a tyrosine kinase, might function as direct upstream activators for MAP kinases. In this paper, however, we revealed that a single 45-kilodalton protein factor from Xenopus-mature oocytes is sufficient for activation of ...
