BLASTanalysis of the human and mouse genome sequence databases using the sequence of the human CMP-sialic acid:b-galactoside a-2,6-sialyltransferase cDNA (hST6Gal I, ) as a probe allowed us to identify a putative sialyltransferase gene on chromosome 2. The sequence of the corresponding cDNA was also found as an expressed sequence tag of human brain.