GENOMIC ORGANIZATION AND CHROMOSOMAL LOCALIZATION OF THE MURINE EPIDIDYMAL RETINOIC-ACID BINDING-PROTEIN (ME-RABP) GENE

The murine epididymal retinoic acid-binding protein (mE-RABP) is speci fically synthesized in the mouse mid/distal caput epididymidis and sec reted in the lumen. In this report, we have demonstrated by Southern b lot analysis of genomic DNA that mE-RABP is encoded by a single-copy g ene. A mouse 129/SvJ genomic bacterial artificial chromosome (BAC) lib rary was screened using a cDNA encoding the minor form of mE-RABP. One positive BAC clone was characterized and sequenced to determine the n ucleo tide sequence of the entire mE-RABP gene. The molecular cloning of the mE-RABP gene completes the characterization of the 20.5-kDa-pre dicted preprotein leading to the minor and major forms of mE-RABP. Com parison of the DNA sequence of the promoter and coding regions with th at of the rat epididymal secretory protein I (ESP I) gene showed that the mE-RABP gene is the orthologue of the ESP I gene that encodes a va t epididymal retinoic acid-binding protein. Several regulatory element s, including a putative androgen receptor binding site, ''CACCC-boxes' ', NF-1, Oct-1, and SP-1 recognition sites, are conserved in the proxi mal promoter Analysis of the nucleotide sequence of the mE-RABP gene r evealed the presence of seven exons and showed that the genomic organi zation is highly related to other genes encoding lipocalins. The mE-RA BP gene was mapped by fluorescent in situ hybridization to the [A3-B] region of the murine chromosome 2. Our data, combined with that of oth ers, suggest that the proximal segment of the mouse chromosome 2 may b e a rich region for genes encoding lipocalins with a genomic organizat ion highly related to the mE-RABP gene. Mol. Reprod. Dev. 50.387-395, 1998. (C) 1998 Wiley-Liss, Inc.