Cubilin

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Cubilin
Properties of human protein
Mass / length primary structure 3588 amino acids
Cofactor Ca 2+
Identifier
Gene name CUBN
External IDs
Occurrence
Homology family Cubilin
Parent taxon Jaws

Cubilin ( gene name: CUBN ), also intrinsic factor-cobalamin receptor , is a protein in the cell membrane of several tissues and acts as a receptor . It is one of two main proteins involved in endocytosis . Cubilin occurs in all jaws and therefore also in humans. Mutations in the CUBN gene can cause cubilin deficiency, and this proteinuria and the rare familial megaloblastic anemia type 1 (MGA1).

Cubilin occurs in tissue types that have an absorptive function, such as intestinal epithelium , kidney epithelium , biliary epithelium or in the yolk sac of the embryo . Cubilin binds to the outer side of the membrane to transport proteins , the lipids , calcidiol , cobalamin transport and other materials and keeps these materials firmly to the cell. The cubilin complex is then transported into the interior of the cell as a vesicle .

function

Cubilin binds to the intrinsic factor : cobalamin complex in the intestine, the amnionless : cobalamin complex in the blood, to light immunoglobulin chains , albumin and hemoglobin , the DBP : calcidiol complex, as well as apolipoprotein A1 and uteroglobin in the uterus. Cubilin forms a complex with LRP1 and LRP2 ( Megalin ). In either case, calcium is required for binding. The binding to Megalin leads to endocytosis of the membrane section and thus to the absorption of all substances bound to it into the cell. The cubilin: megalin complex may also be necessary to prevent gallstones .

regulation

The activity and expression of cubilin and megalin is stimulated by tretinoin and is therefore increased in dividing and cancer cells. The expression of cubilin in the kidneys increases with age, probably to compensate for the increasing number of defects in the large protein.

Individual evidence

  1. ↑ a b c UniProt O60494
  2. ↑ Christensen EI, Nielsen R: Role of megalin and cubilin in renal physiology and pathophysiology . In: Rev. Physiol. Biochem. Pharmacol. . 158, 2007, pp. 1-22. PMID 17729440 .
  3. ↑ Tsaroucha AK, Chatzaki E, Lambropoulou M, et al : Megalin and cubilin in the human gallbladder epithelium . In: Clin. Exp. Med. . 8, No. 3, September 2008, pp. 165-70. doi : 10.1007 / s10238-008-0174-y . PMID 18791690 .
  4. ↑ Kozyraki R, Gofflot F: Multiligand endocytosis and congenital defects: roles of cubilin, megalin and amnionless . In: Curr. Pharm. Des. . 13, No. 29, 2007, pp. 3038-46. PMID 17979745 .
  5. ↑ Chlon TM, Taffany DA, Welsh J, Rowling MJ: Retinoids modulate expression of the endocytic partners megalin, cubilin, and disabled-2 and uptake of vitamin D-binding protein in human mammary cells . In: J. Nutr. . 138, No. 7, July 2008, pp. 1323-8. PMID 18567755 . PMC 2443692 (free full text).
  6. ↑ Odera K, Goto S, Takahashi R: Age-related change of endocytic receptors megalin and cubilin in the kidney in rats . In: Biogerontology . 8, No. 5, October 2007, pp. 505-15. doi : 10.1007 / s10522-007-9093-7 . PMID 17453355 .

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