Catalytic domain of the Serine/Threonine Kinase, BRI1 associated kinase 1 and related STKs
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. This subfamily includes three leucine-rich repeat receptor-like kinases (LRR-RLKs): Arabidopsis thaliana BAK1 and CLAVATA1 (CLV1), and Physcomitrella patens CLL1B clavata1-like receptor S/T protein kinase. BAK1 functions in various signaling pathways. It plays a role in BR (brassinosteroid)-regulated plant development as a co-receptor of BRASSINOSTEROID (BR) INSENSITIVE 1 (BRI1), the receptor for BRs, and is required for full activation of BR signaling. It also modulates pathways involved in plant resistance to pathogen infection (pattern-triggered immunity, PTI) and herbivore attack (wound- or herbivore feeding-induced accumulation of jasmonic acid (JA) and JA-isoleucine. CLV1, directly binds small signaling peptides, CLAVATA3 (CLV3) and CLAVATA3/EMBRYO SURROUNDING REGI0N (CLE), to restrict stem cell proliferation: the CLV3-CLV1-WUS (WUSCHEL) module influences stem cell maintenance in the shoot apical meristem, and the CLE40 (CLAVATA3/EMBRYO SURROUNDING REGION40) -ACR4 (CRINKLY4) -CLV1- WOX5 (WUSCHEL-RELATED HOMEOBOX5) module at the root apical meristem. The STK_BAK1-like subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
Jiyao W et al.(2023). "The conserved domain database in 2023.",