A receptor-like cytoplasmic kinase PCRK2 undergoes ubiquitination and proteasomal degradation

Receptor-like cytoplasmic kinase (RLCK) subfamily VII members are involved in diverse biological processes, like reproduction, immunity, growth and development. Ubiquitination and proteasomal degradation of a RLCK VII member, BOTRYTIS-INDUCED KINASE1 (BIK1) play important roles in regulating immune signaling. It remains largely unknown whether most other RLCK VII members undergo ubiquitination and proteasomal degradation. Here, we select the 6-member RLCK VII-4 to examine the potential proteasomal degradation of its members. We find that three closely related RLCK VII-4 members, PBL38 (AvrPphB SUSCEPTIBLE1-LIKE38), PCRK1 (PTI-COMPROMISED RECEPTOR-LIKE CYTOPLASMIC KINASE1), and PCRK2 are under proteasomal control, while the other members in this group are not. Moreover, we demonstrate that PCRK2 undergoes ubiquitination and proteasomal in a kinase activity-dependent manner. However, the plasma membrane (PM) localization of PCRK2 is not required for its degradation. Our work suggests that many other RLCK VII members may undergo ubiquitination and proteasomal degradation to modulate their homeostasis and cellular functions.