Progress in Studies of Plant Homologs of Mitogen-Activated Protein (MAP) Kinase and Potential Upstream Components in Kinase Cascades

Abstract

Abstract Mitogen-activated protein (MAP) kinase cascades were originally identified as protein phosphorylation systems that control the division and the growth of yeast and animal cells. Such cascades consist of MAP kinases, MAP-kinase kinases, and MAP-kinase-kinase kinases. In addition, these organisms have been also shown to have structurally related but functionally different MAP kinase cascades, which are involved in various cellular processes such as a response to osmotic stress and apoptosis. Plants also have been shown to have a number of members of each kinase family. Although physiological and genetic functions of most plant members have yet to be established, some of members have been shown to be responsible for the cellular transmission of signals generated by wounding or a mechanical stress, which predicts that MAP kinase cascades may function in a variety of physiological processes in the plant cells. In the present review, we summarize recent progresses of researches on plant members of each kinase family as well as those of analyses of the cascades in other organisms.