A. Orellana et al., MOLECULAR-CLONING AND EXPRESSION OF A GLYCOSAMINOGLYCAN N-ACETYLGLUCOSAMINYL N-DEACETYLASE N-SULFOTRANSFERASE FROM A HEPARIN-PRODUCING CELL-LINE, The Journal of biological chemistry, 269(3), 1994, pp. 2270-2276
Heparin has a higher content of N-sulfated glucosamine and L-iduronic
acid than heparan sulfate. Deacetylation of N-acetylglucosamine follow
ed by N-sulfation may be important steps differentiating the biosynthe
sis of these glycosaminoglycans. We have cloned, by cross-hybridizatio
n with the cDNA from rat liver heparan sulfate N-deacetylase/N-sulfotr
ansferase, a protein from a heparin synthesizing mastocytoma derived c
ell line called MST. This protein, which has both N-deacetylase/N-sulf
otransferase activities, has a predicted amino acid sequence homology
of 70% with the above rat liver enzyme and is unique for the following
reasons. 1) It was found to be encoded by a 3.8-kilobase mRNA that wa
s unique to heparin-producing cells; 'an 8.5-kilobase mRNA encoding th
e rat liver enzymes has been found to occur in all mammalian cells tes
ted on the basis of nucleic acid cross-hybridization; 2) the protein o
ver-expressed in COS cells in its full-length transmembrane form or as
a soluble secreted protein A chimera displayed ratios of N-deacetylas
e to N-sulfotransferase activities that were 4-8-fold higher than that
observed for the enzyme found in liver that is involved in the biosyn
thesis of heparan sulfate. These results suggest that the MST-derived
enzyme is probably unique to the production of heparin in mast cells.