GENOMIC STRUCTURE OF HUMAN LYSOSOMAL GLYCOSYLASPARAGINASE

The gene structure of the human lysosomal enzyme glycosylasparaginase was determined. The gene spans 13 kb and consists of 9 exons. Both 5' and 3' untranslated regions of the gene are uninterrupted by introns. A number of transcriptional elements were identified in the 5' upstream sequence that includes two putative CAAT boxes followed by TATA-like sequences together with two AP-2 binding sites and one for Spl. A 100 bp CpG island and several ETF binding sites were also found. Additional AP-2 and Spl binding sites are present in the first intron. Two polyadenylation sites are present and appear to be functional. The major known glycosylasparaginase gene defect G488 --> C, which causes the lysosomal storage disease aspartylglycosaminuria (AGU) in Finland, is located in exon 4. Exon 5 encodes the post-translational cleavage site for the formation of the mature alpha/beta subunits of the enzyme as well as a recently proposed active site threonine, Thr206.