[The identification of repetitive sequences and internal symmetry in the primary structure of N-acetylglucosaminyl-1-phosphotransferases].

UDP-GlcNAc: Dol-P GlcNAc-1-P-transferases (GPT) are the high conservative family of enzymes which catalyze the first reaction of Dol-PP-GlcNAc2Man9Glc3 biosynthesis. This oligosaccharide is necessary for protein N-glycosylation taking place in the endoplasmic reticulum of eucaryotic cells. The analysis of amino acid codon roots made it possible to identify symmetrical segments in the primary structure of GPT. The centres of symmetry of these segments are mainly localized in potential membrane-spanning hydrophobic regions of proteins participating in dolychol-binding regions forming both catalytic and allosteric domains of GPT. Two types of repeating homologous amino acid sequences of yeast GPT are revealed by using graphic method of primary structure analysis. The first type is mainly characterised by the prevalence of hydrophobic amino acids and forms potential transmembrane domains. Hydrophilic amino acids forming hydrophilic loop in C-terminal region of GPT are present in the second type. These sequences consist of 15-18 amino acids residues and occupy more than two-thirds of enzymic molecule.