Putative E3 ubiquitin-protein ligase involved in the rhizobial infection process. Plays an important role in the early steps of infection thread formation and in growth and differentiation of nodules. 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. Expressed in roots and nodules, and at very low levels in calli and seedling shoots. Expressed at all stages of nodule development. By rhizobial infection. In roots, expression increases up to fivefold at 3-7 days post-inoculation (dpi), with further increase at 12 dpi. Truncated N-terminus. Truncated N-terminus.