The APEX Approaches: A Unified LRR-RK Network Revealed

Abstract

Leucine-rich repeat receptor kinases (LRR-RKs) represent a large and functionally diverse family of transmembrane proteins critical for signal recognition and transduction at the plant cell plasma membrane. Here, we discuss a recent report which used a systems-level approach to validate key paradigms by constructing an LRR-RK interaction network model.

APEX as a connector of receptor subnetworks.

The short LRR-RK APEX (center; red), was demonstrated to act as an articulation point in the LRR-RK cell-surface interaction network. The interconnectedness of the various receptor subnetworks (represented top left/right) was predicted to largely rely on APEX and short LRR-RKs like it. APEX likely acts in a manner similar to BAK1 by complexing with several LRR-RKs (represented left/right; green/blue) or indirectly affecting the integrity of other subnetworks. Examples of features which govern the interaction specificity and affinity for the formation of these co-receptor complexes (ligand-induced heterodimerization, transmembrane-helix interactions, intracellular kinase trans-phosphorylation) are labeled throughout the figure. The illustrated LRR-RK models do not represent true molecular structures.