Ubiquitin ligase protein that mediates monoubiquitination of FANCD2 in the presence of UBE2T, a key step in the DNA damage pathway (PubMed:12973351, PubMed:16916645, PubMed:17938197, PubMed:19111657, PubMed:24389026). Also mediates monoubiquitination of FANCI (PubMed:19589784). May stimulate the ubiquitin release from UBE2W. May be required for proper primordial germ cell proliferation in the embryonic stage, whereas it is probably not needed for spermatogonial proliferation after birth. {ECO:0000269|PubMed:12973351, ECO:0000269|PubMed:16916645, ECO:0000269|PubMed:17938197, ECO:0000269|PubMed:19111657, ECO:0000269|PubMed:19589784, ECO:0000269|PubMed:24389026}. This is the function of ENSG00000115392 (FANCL, FA complementation group L).