Membrane receptor dynamics in plants
In plants, there are more than 400 receptor-like kinases (RLKs) that make it the largest family of membrane receptors. By sheer numbers and range of function, they are involved in almost all aspects of plant life including reproduction, development and immunity. The RLK NEGREG (Mechanisms and functions of receptor-like kinase (RLK) negative regulation in plant development) project studied the activation mechanisms for RLKs. To do this, they combined biochemistry, genetics and cell biology and focused on a negative regulator BKI1. BKI1 is the funding member of a small family of related proteins called membrane associated kinase regulators (MAKRs). The project team also worked on the role of a type of phospholipid, specifically phosphatidylinositolphosphates (PIPs) in BKI1/MAKR function. Using genetically encoded biosensors, their results showed that there are gradients for two of these PIPs within the cell. PI4P, for example, has the highest concentration at the plasma membrane, intermediate levels in post-Golgi apparatus/endosomal compartments and lowest in the Golgi. PIPs also have a role in landmarks of various parts of the cell. The researchers found that the plasma membrane (PM) and the cell plate between dividing cells have a unique electrostatic signature controlled by PI4P. Moreover, PI4P accumulates in huge concentrations at the PM. The scientists expect that this property will control the proteins involved in many cell functions including reproduction and nutrition. More work on the 'PIPline' revealed that activity in one cascade in non-stressed root epidermal cells PI(4,5)P2 is able to drive PIP2-interacting protein domains to the plasma membrane. The project has added their findings to the library of PIP marker sets. RLK NEGREG has collaborated with many labs that have established marker sets for functional genomic analysis in Arabidopsis root tissues. They also contributed to the European Arabidopsis Stock Centre. Project research has featured in peer-reviewed journals including Nature Plants and Plant Journal. Their work stands to benefit the whole of the scientific community research on membrane receptors.
Keywords
Membrane receptor, receptor-like kinases, RLK NEGREG, phosphatidylinositolphosphates, PIP marker sets
