CHARACTERIZATION AND SEQUENCE-ANALYSIS OF THE HUMAN HOMEOBOX-CONTAINING GENE GBX2

Polymerase chain reaction (PCR) was used to amplify portions of homeob ox genes present in a human Ii-week fetal brain cDNA library. One of t hese PCR products was determined by sequencing to be the Gastrulation and brain specific-2 gene (GBX2), Screening this human fetal brain cDN A library with probes specific for GBX2 led to the identification of a 2151-bp cDNA clone, The nucleotide sequence of the cDNA clone encodes for a protein of 347 amino acid residues. The amino acid sequence of the GBX2 homeodomain is identical (100%) to the that of homologous gen e, Gbx2, expressed in the developing mouse embryo and virtually identi cal (97%) to a gene expressed in the developing chicken embryo, CHox7, The 5' end of the GBX2 gene contains a CpG island in the untranslated region and a trinucleotide (CCG)(8) repeat in the coding region, The amino-terminal end of the GBX2 protein is proline-rich, with 30 prolin e residues in one stretch of 120 amino acids. A single 2.2-kb transcri pt was detected by Northern analysis in the developing human CNS as we ll as in other tissues. The human genomic clone for GBX2 was also isol ated, characterized, and mapped to 2q36(d)-q37 by somatic cell hybrid analysis and fluorescence in situ hybridization, These studies provide a framework for designing future experiments that are needed to deter mine the functional significance of this gene in CNS development. (C) 1996 Academic Press, Inc.