Could be involved in the negative regulation of root growth. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with KCBP (PubMed:10788494, PubMed:25262228). Interacts with PERK8, PERK9, PERK10 AND PERK13 (PubMed:25262228). Predominantly in the nucleus. Expressed in roots, cauline leaves, flowers and siliques. Autophosphorylated. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Truncated N-terminus.