May act as an E3 ubiquitin-protein ligase and a transcriptional repressor (By similarity). Involved in the regulation of embryonic and adult hematopoiesis. Required for normal development and survival of both committed erythroid progenitor cells and posterior mesenchymal cells. 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 both maternally and throughout the embryo during blastula stage. During gastrulation and epiboly stages, strongly expressed in the mesendoderm of the germ ring. Expressed at the tail bud and in early somite stages in a horseshoeshaped population of ventral/lateral mesoderm cells that will give rise to blood. Detected in ventral-lateral mesoderm between the one- to three-somite stages and increases through early development. Expressed in lateral stripes of mesoderm at five somites. Expressed broadly in the brain, spinal cord, trunk, and tail mesenchyme, but is at much higher levels in hematopoietic cells of the blood island at 24-72 hours post-fertilization (hpf).