Organization of the mouse GP42/Basigin gene: a member of the Ig superfamily.

We have mapped and sequenced the GP42/Basigin gene isolated from a Balb/C mouse genomic library. The genomic organization and upstream, putative regulatory, regions of this gene have not been previously reported. Our data show that exon 5 of the GP42/Basigin gene encodes the carboxy proximal half of the second Ig-like domain, the highly conserved transmembrane region and a portion of the cytoplasmic tail. This inclusion of Ig-like and other functional domains in a single exon is unusual. Splice junction analysis indicates that two reported alternate GP42/Basigin cDNA isoforms are likely due to cloning artifacts. In addition, we find that GP42/Basigin is polymorphic in mice. Our data also support the proposal that the transmembrane domain and portions of the cytoplasmic region of GP42/Basigin have been evolutionarily conserved.