Functions as an E3 ubiquitin ligase. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. The protein kinase domain is predicted to be catalytically inactive. May be due to a competing acceptor splice site. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. The predicted gene At3g49060 has been split into 2 genes: At3g49055 and At3g49060.