Human Apolipoprotein D Gene: Gene Sequence, Chromosome Localization, and Homology to the α_2u-Globulin Superfamily

The exons and bordering intron nucleotides of the human apolipoprotein D (apo D) gene have been sequenced. The protein-coding portion of the gene is divided into five exons which span ∼12,000 bp. At least one intron interrupts the 5′ untranslated region. The gene has been localized to the pl4.2→qter region of human chromosome 3. Apo D shares homology with the α_2u-globulin superfamily of genes, including ∼25% amino acid homology with human retinol-binding protein (RBP). Similarity of intron locations in both apo D and RBP suggests that these two genes derived from a common ancestor.