MOLECULAR-CLONING AND CHROMOSOMAL LOCALIZATION OF A PSEUDOGENE RELATED TO THE HUMAN ACYL-COA-BINDING PROTEIN DIAZEPAM-BINDING INHIBITOR

The acyl-CoA binding protein (ACBP) and the diazepam binding inhibitor (DBI) or endozepine are independent isolates of a single 86-amino-aci d, 10-kDa protein. ACBP/DBI is highly conserved between species and ha s been identified in several diverse organisms, including human, cow, rat, frog, duck, insects, plants, and yeast. Although the genomic locu s has not yet been cloned in humans, complementary DNA clones with dif ferent 5' ends have been isolated and characterized. These cDNA clones appear to be encoded by a single gene. However, Southern blot analyse s, in situ hybridizations, and somatic cell hybrid chromosomal mapping all suggest that there are multiple ACBP/DBI-related sequences in the genome. To identify potential members of this gene family, degenerate oligonucleotides corresponding to highly conserved regions of ACBP/DB I were used to screen a human genomic DNA library using the polymerase chain reaction. A novel gene, DBIP1, that is closely related to ACBP/ DBI but is clearly distinct was identified. DBIP1 bears extensive sequ ence homology to ACBP/DBI but lacks the introns predicted by rat and d uck genomic sequence studies. A 1-base deletion in the coding region r esults in a frameshift and, along with the absence of introns and the lack of a detectable transcript, suggests that DBIP1 is a pseudogene. ACBP/DBI has previously been mapped to chromosome 2, although this was recently disputed, and a chromosome 6 location was suggested. We show that ACBP/DBI is correctly placed on chromosome 2 and that the gene i dentified on chromosome 6 is DBIP1. (C) 1995 Academic Press, Inc.