Exploring the evolutionary path of plant MAPK networks.

The evolutionarily conserved mitogen-activated protein kinase (MAPK) signaling network comprises connected protein kinases arranged in MAPK modules. In this Opinion article, we analyze MAPK signaling components in evolutionarily representative species of the plant lineage and in Naegleria gruberi, a member of an early diverging eukaryotic clade. In Naegleria, there are two closely related MAPK kinases (MKKs) and a single conventional MAPK, whereas in several species of algae, there are two distinct MKKs and multiple MAPKs belonging to different groups.

Comprehensive gene expression atlas for the Arabidopsis MAP kinase signalling pathways.

* Mitogen activated protein kinase (MAPK) pathways are signal transduction modules with layers of protein kinases having c. 120 genes in Arabidopsis, but only a few have been linked experimentally to functions. * We analysed microarray expression data for 114 MAPK signalling genes represented on the ATH1 Affymetrix arrays; determined their expression patterns during development, and in a wide range of time-course microarray experiments for their signal-dependent transcriptional regulation and their coregulation with other signalling components and transcription factors.

Learning the lipid language of plant signalling.

Plant cells respond to different biotic and abiotic stresses by producing various uncommon phospholipids that are believed to play key roles in cell signalling. We can predict how they work because animal and yeast proteins have been shown to have specific lipid-binding domains, which act as docking sites. When such proteins are recruited to the membrane locations where these phospholipids are synthesized, the phospholipids activate them directly, by inducing a conformational change, or indirectly, by juxtaposing them with an activator protein.

Growth signalling pathways in Arabidopsis and the AGC protein kinases.

Lipid-derived signals are central to regulating a multitude of cellular processes but, in plants, little is known of the downstream signalling pathways. The Arabidopsis 3-phosphoinositide-dependent protein kinase (PDK1) could couple lipid signals to the activation of several protein kinases of the so-called AGC kinase family. The Arabidopsis AGC kinases contain sequence motives required for the docking of PDK1 and phosphorylation of their activation loop in the kinase catalytic domain.

First glance at the plant APC/C, a highly conserved ubiquitin-protein ligase.

The anaphase-promoting complex or cyclosome (APC/C) is a cell-cycle-regulated ubiquitin-protein ligase that has been extensively studied in both fungal and animal cells. Many APC/C protein targets have been identified, and their sequential degradation during the cell cycle is essential for chromatid separation and mitotic exit. APC/C-dependent ubiquitylation of proteins not involved in cell-cycle progression has also been documented in animal cells.