Tissue specific expression and chromosomal mapping of a human UDP-N-acetylglucosamine:α1,3-d-mannoside β1,4-N-acetylglucosaminyltransferase

A human cDNA for UDP-N-acetylglucosamine:α1,3-D-mannoside β1,4-N-acetylglucosaminyltransferase (GnT-IV) was isolated from a liver cDNA library using a probe based on a partial cDNA sequence of the bovine GnT-IV. The cDNA encoded a complete sequence of a type II membrane protein of 535 amino acids which is 96% identical to the bovine GnT-IV. Transient expression of the human cDNA in COS7 cells increased total cellular GnT-IV activity 25-fold, demonstrating that this cDNA encodes a functional human GnT-IV. Northern blot analysis of normal tissues indicated that at least five different sizes of mRNA (9.7, 7.6, 5.1, 3.8, and 2.4 kb) for GnT-IV are expressed in vivo. Furthermore, these mRNAs are expressed at different levels between tissues. Large amounts of mRNA were detected in tissues harboring T lineage cells. Also, the promyelocytic leukemia cell line HL-60 and the lymphoblastic leukemia cell line MOLT-4 revealed abundant mRNA. Lastly, the gene was mapped at the locus on human chromosome 2, band q12 by fluorescent in situ hybridization.