Chromosomal Localization of Human Genes for the LDL Receptor Family Member Glycoprotein 330 (LRP2) and Its Associated Protein RAP (LRPAP1)

Glycoprotein 330 (gp330) is a member of a family of receptors with structural similarities to the low-density lipoprotein receptor. Gp330 is expressed by a number of specialized epithelia, including renal proximal tubules, where it can mediate endocytosis of ligands such as complexes of urokinase and the serpin, plasminogen activator inhibitor-1. Gp330 has also been shown to bind in vitro to lipoprotein lipase and apolipoprotein E-enriched beta VLDL, suggesting a role for this receptor in lipoprotein metabolism. The 39-kDa protein, referred to as receptor associated protein (RAP), binds to and copurifies with gp330 and antagonizes the ligand binding activity of gp330. In this paper, we report the use of homology-PCR cloning to isolate cDNAs encoding human gp330. Using gp330 cDNA and previously isolated human RAP cDNA probes, we performed fluorescence in situ hybridization to map the human chromosomal location of the genes for these proteins. The gene for gp330 was mapped at a single site on the long arm of human chromosome 2 on the border of bands 2q24-q31. The gene for RAP was mapped to the short arm of human chromosome 4 at position 4p16.3, which is in the region of the chromosomal deletion causing Wolf-Hirschhorn syndrome. The assignment of chromosomal map positions for gp330 and RAP genes will aid in the evaluation of their potential roles in human diseases such as Wolf-Hirschhorn syndrome and disorders of lipoprotein metabolism, such as atherosclerosis.