CHARACTERIZATION OF A HUMAN HOMOLOG (BACH1) OF THE MOUSE BACH1 GENE ENCODING A BTB BASIC LEUCINE-ZIPPER TRANSCRIPTION FACTOR AND ITS MAPPING TO CHROMOSOME 21Q22.1

Clinical interest in the genes on human chromosome 21, especially with respect to Down syndrome (DS), has provided a strong impetus for the creation of a transcript map of this chromosome. In an effort to ident ify new human genes on the basis of cDNA analysis, we found several cD NA clones that corresponded to chromosome 21-specific transcripts. One of these, ha2303, showed strong similarity to the murine transcriptio n factor Bach1. We subsequently determined the entire nucleotide seque nce of this cDNA clone and found it to contain the whole coding sequen ce. The gene, termed BACH1, encodes a 736-amino-acid polypeptide with 80.3% identity to the murine Bach1 protein and contains a Cap'n'collar (CNC)-type basic leucine zipper (bZip) domain and a protein interacti on motif, the BTB domain. Northern blot analysis revealed that BACH1 w as expressed in all tissues examined. Mapping using the NotI restricti on map and the YAC contig map showed that the BACH1 gene is located at 21q22.1 between the NotI sites LA329 (D21S338) and LL60 (D21S389) and within approximately 400 kb of LA329. Both the prospective function a nd the chromosomal location suggest that this gene may be a DS candida te gene, contributing to certain DS phenotypes, and is possibly involv ed in certain features of monosomy 21. (C) 1998 Academic Press.