Human N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase cDNA is relatedto human B cell recombination activating gene-associated gene

N-Acetylgalactosamine 4-sulfate 6-O-sulfotransferase (Ga1NAc4S-6ST) transfe rs sulfate from 3'-phosphoadenosine 5'-phosphosulfate to position 6 of N-ac etylgalactosamine 4-sulfate (Ga1NAc(4SO(4))) in chondroitin. sulfate and de rmatan sulfate. We have previously purified the enzyme to apparent homogene ity from the squid cartilage. We report here cloning and characterization o f human Ga1NAc4S-6ST. The strategy for identification of human Ga1NAc4S-6ST consisted of. 1) determination of the amino acid sequences of peptides der ived from the purified squid Ga1NAc4S-6ST, 2) amplification of squid DNA by polymerase chain reaction, and 3) homology search using the amino acid seq uence deduced from the squid DNA. The human Ga1NAc4S-6ST cDNA contains a si ngle open reading frame that predicts a type H transmembrane protein compos ed of 561 amino acid residues. The recombinant protein expressed from the h uman Ga1NAc4S-6ST cDNA transferred sulfate from 3'-phosphoadenosine 5'-phos phosulfate to position 6 of the nonreducing terminal and internal Ga1NAc(4S O(4)) residues contained in chondroitin sulfate A and dermatan sulfate. Whe n a trisaccharide and a pentasaccharide having sulfate groups at position 4 of N-acetylgalactosamine residues were used as acceptors, only nonreducing terminal Ga1NAc(4SO(4)) residues were sulfated. The nucleotide sequence of the human Ga1NAc4S-6ST cDNA was nearly identical to the sequence of human B cell recombination activating gene-associated gene.