Megalin (also low-density lipoprotein receptor- related protein 2, LRP2 ), is a protein in the cell membrane of multiple tissues, a so-called receptor. It is one of two responsible for endocytosis proteins in bilaterians, and thus also in humans. Mutations in the gene LRP2 can Megalinmangel and this lead to proteinuria and rare Donnai - Barrow syndrome, a severe developmental impairment.

Megalin belongs to a family of receptors that have structural similarity to the LDL receptor. With 4630 amino acids, it is a very large protein.


Megalin is mainly found in Epithelgewebemembranen and ensures there together with his partner, cubilin by membrane transport ( endocytosis ) for the absorption of many substances into the cell. Megalin not only binds to cubilin, which acts itself as a receptor for many lipid, hormone and vitamin -transporting complexes. Megalin also binds itself to lipids, coagulation factors, VLDL, albumin, lactoferrin, selenoprotein P and clusterin. The cubilin: megalin complex is mainly responsible for the uptake of cobalamin in the intestine of proteins, lipids, calcidiol and iron from the blood, and the retention of most of the substances mentioned in the proximal tubule cells.

The cubilin: megalin complex may be necessary to prevent gallstones. Variants of megalin is associated with the occurrence, the course and the effectiveness of the therapy of prostate cancer. By binding to metallothionein megalin plays a role in the development of astrocytes.


The activity and expression of megalin cubilin and is excited by tretinoin and is thus increased in dividing cells and cancer cells. The expression of megalin in the kidneys is increased in old age, probably to compensate for the increasing number of defects at the large protein.