Abstract
The low-density lipoprotein receptor gene family encompasses a class of endocytic receptors that exhibit structural similarities to the low-density lipoprotein receptor. Members of this gene family are present in both vertebrate and nonvertebrate species. The identification of naturally occurring mutations and the application of gene targeting to inactivate receptor genes enabled us to develop animal models to investigate the consequences of individual receptor defects in vivo. Analysis of these animal models revealed exciting new functions of lipoprotein receptors not only in systemic clearance of lipoproteins but also in other important biological processes including reproduction, brain development. and adipositas.