Organization of the human N-acetylglucosaminyltransferase V gene.

UDP-N-acetylglucosamine: alpha-6-D-mannoside beta-1,6-N-acetylglucosaminyltransferase V (GlcNAc transferase V), which catalyzes the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to alpha-6-D-mannoside, is an important enzyme regulating the branch formation in complex-type, N-linked oligosaccharides. It has been reported that the enzymic activity of GlcNAc transferase V increases after viral transformation and the enzymic product is closely related to the metastasis of tumors. We previously reported the purification, cDNA cloning and chromosomal mapping of human GlcNAc transferase V. In this study, we describe the isolation of genomic clones encoding human GlcNAc transferase V and the structure of the gene. The human GlcNAc transferase V gene is divided into 17 exons, and the open reading frame is encoded by exons 2-17, spanning 155 kb. Analysis of the 5'-untranslated regions of mRNAs from various cells showed multiple sequences depending on the cell types. The promoter region of the GlcNAc transferase V gene was characterized by searching for any consensus sequences matching those for transcription-factor binding. The consensus sequences for a TATA box, AP-1, AP-2, and some other transcription factors were found in the 5'-upstream region of exon 1, and consensus sequences for LF-A1, HNF1-HP1, liver-restricted transcription factors and other factors were also found in intron 1. Chloramphenicol acetyltransferase fusion plasmids with either the 5'-upstream region of exon 1 or intron 1 were constructed and transfected into COS-1 cells. Promoter activities of both DNA fragments were detected, indicating that transcription starts within this region. These data suggest that the human GlcNAc transferase V gene employs a multiple promoter system for its transcription, and gene expression may therefore be regulated in tissue-specific and cell-type-specific manners.