Update on Plasma Membrane Receptor Complexes Plasma Membrane Receptor Complexes

Recent data on the plasma membrane (PM)-located LRR-RLKs (for Leu-rich repeat receptor-like kinases) BRI1 (for brassinosteroid insensitive 1) and the coreceptors BAK1 (for BRI1-associated kinase 1) and SERK1 (for somatic embryogenesis receptor-like kinase 1) that participate in the perception of brassinosteroids (BRs) suggest that they are organized into heterooligomeric protein complexes. Other components of this complex include members of the 14-3-3 family, and, in the case of SERK1, the kinase-associated protein phosphatase (KAPP) and the AAA ATPase cell division cycle 48A (CDC48A). CDC48 proteins interact with ubiquitinated target proteins in animal and plant cells. In this Update we describe the role of several of the nonreceptor partners of the PM receptor complex with an emphasis on the role of CDC48 proteins in translocation and ubiquitination as a proposed mode of regulation of plant PM receptors.