Molecular Cloning of Mouse Lrp7(Lr3) CDNA and Chromosomal Mapping of Orthologous Genes in Mouse and Human

LRP7 (the HGMW-approved gene symbol for LR3) is a novel member of the low-density lipoprotein receptor (LDLR) family. The unique modular features in both its extracellular and its intracellular regions and functional analysis suggest it to be a multifunctional protein with mitogenic activity and potential ligand-induced signal transduction capability. We describe here the cloning of Lrp7, the orthologue of the human LRP7 gene, from a mouse liver cDNA library and its expression profile in mouse tissues and developmental stages. Lrp7 is highly homologous to the human sequence, with 95% identity at the amino acid level and a perfect conservation of all the recognizable functional domains. A 6-kb mRNA transcript could be detected in all the tissues examined, with the highest expression levels in liver, heart, and lung and the lowest levels in brain and spleen. A similar expression level of a smaller transcript (4.5 kb) was seen at the four embryonic stages examined. We mapped the Lrp 7 gene to mouse chromosome 19B and the LRP7 gene to human chromosome 11q13.4. The LRP7 gene was also localized by radiation hybrid mapping between markers D11S24270 and D11S1975.