MOLECULAR-CLONING OF A HUMAN GENOMIC REGION CONTAINING THE H-BLOOD-GROUP ALPHA(1,2)FUCOSYLTRANSFERASE GENE AND 2 H-LOCUS-RELATED DNA RESTRICTION FRAGMENTS - ISOLATION OF A CANDIDATE FOR THE HUMAN SECRETOR BLOOD-GROUP LOCUS

We have used the human H blood group alpha(1,2)fucosyltransferase (FUT 1) cDNA to screen chromosome 19 cosmid libraries in a search for the h uman Secretor (Se) blood group gene (FUT2), One cosmid has been isolat ed that contains two distinct segments that cross-hybridize with FUT1. We have assembled a 100-kilobase (kb) cosmid contig, localized to 19q 13,3, encompassing FUT1 and the two FUT1-related sequences, termed Sec 1 and Sec2, for Secretor candidate 1 and 2, Sec1 and Sec2 are separate d by 12 kb and are 65.5 kb and 35 kb apart, respectively, from the FUT 1 gene, We used a cosmid-dependent direct cDNA selection method to clo ne a cDNA corresponding to a transcript that emanates from Sec2. This cDNA detects a 3.35-kb transcript in human tissues known to express th e Se locus, Together with sequence and expression data reported in the accompanying article (Kelly, R, J., Rouquier, S., Giorgi, D., Lennon, G. G., and Lowe, J. B. (1995) J. Biol. Chem. 270, 4640-4649), these d ata demonstrate that Sec2 corresponds to the human Se blood group locu s (FUT2), Our results further more define the physical relationship be tween the LT and Se loci and confirm a hypothesis that these two loci represent distinct but closely linked alpha(1,2)fucosyltransferase gen es