Regulation of the MAPK family members: role of subcellular localization and architectural organization.

The members of the mitogen-activated protein kinase (MAPK) family are regulated by a diverse array of extracellular cues ranging from cytokines, growth factors and neuropeptides, which activate cell surface receptors, to stresses such as cold, heat, osmolarity changes and irradiation. The MAPK pathways control genetic expression by modifying transcription factor activity and cue important cell fate decisions including survival, proliferation, and programmed cell death (apoptosis). One interesting feature of the MAPK pathways is that the components are evolutionarily conserved from yeast to human, and many of the pathways are similarly organized and regulated. Unlike previously imagined, architectural organization or the multimeric organization of signaling proteins into complexes which are localized to distinct subcellular regions is an important mechanism that influences the regulation of these pathways. In addition, extracellular stimuli can induce relocalization of specific signal transduction proteins. The formation of multimeric signaling complexes, as well as the dynamic movement of signaling proteins, contribute to determine signaling specificity and efficacy. This review describes what is currently known about the subcellular localization of MAPK pathway signaling proteins and the relocalization that occurs during events associated with activation of the MAPK family members.