Source:http://linkedlifedata.com/resource/umls/id/C1452577
NCI: DNA Methyltransferase 3B, encoded by the human DNMT3B gene, is required for genome wide de novo methylation and is essential for development. This nuclear protein interacts with UBL1 and UBE2I9. Six isoforms (1, 2, 3, 4, 5 and 6) are produced by alternative splicing but isoforms 4 and 5 are probably not functional due to the deletion of two conserved methyltransferase motifs. Isoform 1 is expressed in all tissues except brain, skeletal muscle and PBMC, 3 is ubiquitous, 4 is expressed in all tissues except brain, skeletal muscle, lung and prostate and 5 is detectable only in testis and at very low level in brain and prostate. Defects in DNMT3B are a cause of immunodeficiency-centromeric instability-facial anomalies (ICF) syndrome. ICF is biochemically characterized by hypomethylation of CpG sites in some regions of heterochromatin. (From LocusLink, Swiss-Prot and NCI)