WAKs

Wall-associated kinases (WAKs) are a family of receptor-like kinases in plants that span the plasma membrane and connect the cell wall to the cytoplasm. They are characterized by an extracellular domain that binds components of the cell wall, a single transmembrane segment, and a cytoplasmic serine/threonine kinase domain. In many species, the extracellular region can interact with pectin and other polysaccharides, enabling a direct link between wall status and intracellular signaling.

Functionally, WAKs participate in cell wall integrity sensing and transduction of wall-derived signals that regulate cell expansion, differentiation, and defense responses. Binding of pectin or pectin-derived fragments, such as oligogalacturonides, can activate WAK signaling, leading to changes in gene expression and cellular responses to mechanical stress or pathogen attack. This signaling often involves cooperation with other receptor-like proteins and downstream kinases, connecting extracellular cues to transcriptional programs.

Gene family structure includes several members in Arabidopsis and other plants, commonly grouped into WAKs and WAK-like proteins (WAKLs). While they share the receptor-like kinase topology, their extracellular domains and ligand specificities vary, allowing diverse roles in development and immunity. WAKs are frequently studied for their involvement in growth regulation, tissue patterning, and defense gene networks.

Significance, ongoing research, and comparative studies across species aim to clarify the full scope of WAK signaling, including interaction partners, downstream pathways, and the evolution of this family in relation to plant architecture and stress responses.