Cloning and Functional Expression of a Novel Glucuronyltransferase Involved in the Biosynthesis of the Carbohydrate Epitope HNK-1

• Published in: Proceedings of the National Academy of Sciences - PNAS 1997-06, Vol.94 (12), p.6093-6098
• Main Authors: Terayama, Koji, Oka, Shogo, Seiki, Takashi, Miki, Yukari, Nakamura, Akemi, Kozutsumi, Yasunori, Takio, Koji, Kawasaki, Toshisuke
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; Animals; Base Sequence; Biochemistry; Biological Sciences; Brain - enzymology; CD57 Antigens - analysis; CD57 Antigens - biosynthesis; Cell lines; Cellular biology; Cloning, Molecular; Complementary DNA; COS Cells; Deoxyribonucleic acid; DNA; DNA, Complementary - metabolism; Enzymes; Epitopes; Glucuronosyltransferase - biosynthesis; Glucuronosyltransferase - chemistry; Glucuronosyltransferase - metabolism; Glycoproteins; Insecta; Mammals; Molecular Sequence Data; Nervous system; Nervous System - enzymology; Neurons; Polymerase Chain Reaction; Rats; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Transfection
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.12.6093

The HNK-1 carbohydrate epitope is characteristically expressed on a series of cell adhesion molecules and also on some glycolipids in the nervous system over a wide range of species from insect to mammal. The HNK-1 epitope is involved in cell-cell and/or cell-substrate interaction and recognition during the development of the nervous system. In this study, we isolated a novel glucuronyltransferase from rat brain, which is a key enzyme of the biosynthesis of the HNK-1 epitope on glycoproteins. Based on the partial amino acid sequences, we isolated cDNA encoding the glucuronyltransferase. The primary structure deduced from the cDNA sequence predicted a type II transmembrane protein with 347 amino acids and had no detectable similarity with any other proteins of known functions, including glucuronyltransferases of the liver and olfactory epithelium. Expression of a soluble recombinant form of the enzyme in COS-1 cells produced an active glucuronyltransferase. The selective expression of the glucuronyltransferase gene in the nervous system was consistent with the almost exclusive localization of the HNK-1 epitope in the nervous system. Transfection of the glucuronyltransferase cDNA into COS-1 cells induced not only expression of the HNK-1 epitope on the cell surface but also marked morphological changes of the cells, suggesting that the HNK-1 epitope associates with the cell-substratum interaction.