Involved in the regulation of cellular expansion and differentiation. Mediates subcellular relocalization of PUB9 from nucleus to plasma membrane in a protein-phosphorylation-dependent manner. May be involved in the abscisic acid-mediated signaling pathway, at least during germination. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with PUB9, PUB13, PUB14 and PUB38. Mostly expressed in leaves, and, to a lower extent, in stems and flower buds. By wounding and Xanthomonas campestris pv. campestris. Autophosphorylated on serine and threonine residues. Reduced abscisic acid (ABA) sensitivity during seed germination. Receptor domain alone. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. The predicted gene At1g65790 has been split into 2 genes: At1g65790 and At1g65800.