ISOLATION AND CHARACTERIZATION OF GT335, A NOVEL HUMAN GENE CONSERVEDIN ESCHERICHIA-COLI AND MAPPING TO 21Q22.3

As part of efforts to identify candidate genes for disorders mapped to 21q22.3, we have constructed a 405-kb cosmid contig encompassing five tightly Linked markers mapping to this region A subset of these cosmi ds was used to identify cDNA fragments by the method of hybrid selecti on. We present here the cDNA sequence of one such gene (GT335) mapping to this region. The gene is expressed as a 1.7-kb transcript predomin antly in heart and skeletal muscle, potentially displays alternate spl icing, and is predicted to encode a protein 268 amino acids in length. GT335 spans an estimated 13 kb of genomic DNA and is split into seven exons. Five of the six introns conform to the GT...AG consensus for i ntronic splice junctions; the sixth contains nonconventional (AT...AC) intronic junctions. We screened this gene for single-basepair mutatio ns using single-strand conformation polymorphism and sequence analysis of both cDNA and genomic DNA from a number of unrelated individuals a nd have identified several sequence variations, two of which cause con servative amino acid substitutions. This gene is well conserved evolut ionarily, with homologs identified in zebrafish and Escherichia coli, suggesting that it plays an important role in basic cellular metabolis m. (C) 1996 Academic Press, Inc.