Cubilin, a multifunctional epithelial receptor: an overview

Cubilin is a 460-kDa endocytic receptor coexpressed with megalin, a multili gand receptor of the low-density lipoprotein receptor gene family, at the a pical pole of epithelial cells in the renal proximal convoluted tubule, vis ceral yolk sac, ileum, and placenta. The structure of cubilin is unique: it lacks a transmembrane domain and requires megalin fur its internalization. The accumulation of 27 interactive CUB domains provides the potential for multiple, possibly independent interactions and functions, Cubilin is invol ved in the intestinal absorption of vitamin B-12, the catabolism of apolipo protein A-I by the proximal convoluted tubule and more generally in renal p rotein reabsorption. The role of cubilin on fetomaternal interfaces is not defined but may be related to its ability to bind and internalize high dens ity lipoproteins.