LOCALIZATION OF HUMAN HEPARAN GLUCOSAMINYL N-DEACETYLASE N-SULFOTRANSFERASE TO THE TRANS-GOLGI NETWORK/

In order to determine the intracellular location of heparan N-deacetyl ase/N-sulphotransferase, cDNAs encoding human heparan glucosaminyl N-d eacetylase/N-sulphotransferase were cloned from human umbilical vein e ndothelial cells, The deduced amino acid sequence was identical to tha t of the human heparan N-sulphotransferase cloned previously [Dixon, L oftus, Gladwin, Scambler, Wasmuth and Dixon (1995) Genomics 26, 239-24 4]. RNA blot analysis indicated that two heparan N-sulphotransferase t ranscripts of approx, 8.5 and 4 kb were produced in all tissues. Expre ssion was most abundant in heart, liver and pancreas, A cDNA encoding a Flag-tagged human heparan N-sulphotransferase (where Flag is an epit ope with the sequence DYKDDDDK) was transfected into mouse LTA cells, Immunofluorescence detection using anti-Flag monoclonal antibodies dem onstrated that the enzyme was localized to the trans-Golgi network, A truncated Flag-tagged heparan N-sulphotransferase was also retained in the Golgi, indicating that, as for many other Golgi enzymes, the N-te rminal region of heparan N-sulphotransferase is sufficient for retenti on in the Golgi apparatus.