1de4

Structural highlights

Disease

[HFE_HUMAN] Defects in HFE are a cause of hemochromatosis (HFE) [MIM:235200]. A disorder of iron metabolism characterized by iron overload. Excess iron is deposited in a variety of organs leading to their failure, and resulting in serious illnesses including cirrhosis, hepatomas, diabetes, cardiomyopathy, arthritis, and hypogonadotropic hypogonadism. Severe effects of the disease usually do not appear until after decades of progressive iron loading.^{[1] [2] [3] [4] [5] [6] [7] [8]} [:]^{[9] [10] [11] [12] [13] [14] [15] [16] [17]} Defects in HFE are associated with variegate porphyria (VP) [MIM:176200]. Porphyrias are inherited defects in the biosynthesis of heme, resulting in the accumulation and increased excretion of porphyrins or porphyrin precursors. They are classified as erythropoietic or hepatic, depending on whether the enzyme deficiency occurs in red blood cells or in the liver. VP is the most common form of porphyria in South Africa. It is characterized by skin hyperpigmentation and hypertrichosis, abdominal pain, tachycardia, hypertension and neuromuscular disturbances. High fecal levels of protoporphyrin and coproporphyrin, increased urine uroporphyrins and iron overload are typical markers of the disease. Note=Iron overload due to HFE mutations is a precipitating or exacerbating factor in variegate porphyria. Defects in HFE are associated with susceptibility to microvascular complications of diabetes type 7 (MVCD7) [MIM:612635]. These are pathological conditions that develop in numerous tissues and organs as a consequence of diabetes mellitus. They include diabetic retinopathy, diabetic nephropathy leading to end-stage renal disease, and diabetic neuropathy. Diabetic retinopathy remains the major cause of new-onset blindness among diabetic adults. It is characterized by vascular permeability and increased tissue ischemia and angiogenesis. [B2MG_HUMAN] Defects in B2M are the cause of hypercatabolic hypoproteinemia (HYCATHYP) [MIM:241600]. Affected individuals show marked reduction in serum concentrations of immunoglobulin and albumin, probably due to rapid degradation.^[18] Note=Beta-2-microglobulin may adopt the fibrillar configuration of amyloid in certain pathologic states. The capacity to assemble into amyloid fibrils is concentration dependent. Persistently high beta(2)-microglobulin serum levels lead to amyloidosis in patients on long-term hemodialysis.^{[19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31]}

Function

[HFE_HUMAN] Binds to transferrin receptor (TFR) and reduces its affinity for iron-loaded transferrin.^[32] [TFR1_HUMAN] Cellular uptake of iron occurs via receptor-mediated endocytosis of ligand-occupied transferrin receptor into specialized endosomes. Endosomal acidification leads to iron release. The apotransferrin-receptor complex is then recycled to the cell surface with a return to neutral pH and the concomitant loss of affinity of apotransferrin for its receptor. Transferrin receptor is necessary for development of erythrocytes and the nervous system (By similarity). A second ligand, the heditary hemochromatosis protein HFE, competes for binding with transferrin for an overlapping C-terminal binding site.^[33] [B2MG_HUMAN] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

See Also

• Beta-2 microglobulin 3D structures
• Hemochromatosis protein
• Transferrin receptor

References

1. ↑ Feder JN, Gnirke A, Thomas W, Tsuchihashi Z, Ruddy DA, Basava A, Dormishian F, Domingo R Jr, Ellis MC, Fullan A, Hinton LM, Jones NL, Kimmel BE, Kronmal GS, Lauer P, Lee VK, Loeb DB, Mapa FA, McClelland E, Meyer NC, Mintier GA, Moeller N, Moore T, Morikang E, Prass CE, Quintana L, Starnes SM, Schatzman RC, Brunke KJ, Drayna DT, Risch NJ, Bacon BR, Wolff RK. A novel MHC class I-like gene is mutated in patients with hereditary haemochromatosis. Nat Genet. 1996 Aug;13(4):399-408. PMID:8696333 doi:10.1038/ng0896-399
2. ↑ Carella M, D'Ambrosio L, Totaro A, Grifa A, Valentino MA, Piperno A, Girelli D, Roetto A, Franco B, Gasparini P, Camaschella C. Mutation analysis of the HLA-H gene in Italian hemochromatosis patients. Am J Hum Genet. 1997 Apr;60(4):828-32. PMID:9106528
3. ↑ Roberts AG, Whatley SD, Morgan RR, Worwood M, Elder GH. Increased frequency of the haemochromatosis Cys282Tyr mutation in sporadic porphyria cutanea tarda. Lancet. 1997 Feb 1;349(9048):321-3. PMID:9024376 doi:S0140-6736(96)09436-6
4. ↑ Bonkovsky HL, Poh-Fitzpatrick M, Pimstone N, Obando J, Di Bisceglie A, Tattrie C, Tortorelli K, LeClair P, Mercurio MG, Lambrecht RW. Porphyria cutanea tarda, hepatitis C, and HFE gene mutations in North America. Hepatology. 1998 Jun;27(6):1661-9. PMID:9620340 doi:S0270913998002468
5. ↑ Mura C, Raguenes O, Ferec C. HFE mutations analysis in 711 hemochromatosis probands: evidence for S65C implication in mild form of hemochromatosis. Blood. 1999 Apr 15;93(8):2502-5. PMID:10194428
6. ↑ Barton JC, Sawada-Hirai R, Rothenberg BE, Acton RT. Two novel missense mutations of the HFE gene (I105T and G93R) and identification of the S65C mutation in Alabama hemochromatosis probands. Blood Cells Mol Dis. 1999 Jun-Aug;25(3-4):147-55. PMID:10575540
7. ↑ de Villiers JN, Hillermann R, Loubser L, Kotze MJ. Spectrum of mutations in the HFE gene implicated in haemochromatosis and porphyria. Hum Mol Genet. 1999 Aug;8(8):1517-22. PMID:10401000
8. ↑ Merryweather-Clarke AT, Simonsen H, Shearman JD, Pointon JJ, Norgaard-Pedersen B, Robson KJ. A retrospective anonymous pilot study in screening newborns for HFE mutations in Scandinavian populations. Hum Mutat. 1999;13(2):154-9. PMID:10094552 doi:<154::AID-HUMU8>3.0.CO;2-E 10.1002/(SICI)1098-1004(1999)13:2<154::AID-HUMU8>3.0.CO;2-E
9. ↑ Moczulski DK, Grzeszczak W, Gawlik B. Role of hemochromatosis C282Y and H63D mutations in HFE gene in development of type 2 diabetes and diabetic nephropathy. Diabetes Care. 2001 Jul;24(7):1187-91. PMID:11423500
10. ↑ Imanishi H, Liu W, Cheng J, Ikeda N, Amuro Y, Hada T. Idiopathic hemochromatosis with the mutation of Ala176Val heterozygous for HFE gene. Intern Med. 2001 Jun;40(6):479-83. PMID:11446670
11. ↑ Jones DC, Young NT, Pigott C, Fuggle SV, Barnardo MC, Marshall SE, Bunce M. Comprehensive hereditary hemochromatosis genotyping. Tissue Antigens. 2002 Dec;60(6):481-8. PMID:12542741
12. ↑ Le Gac G, Dupradeau FY, Mura C, Jacolot S, Scotet V, Esnault G, Mercier AY, Rochette J, Ferec C. Phenotypic expression of the C282Y/Q283P compound heterozygosity in HFE and molecular modeling of the Q283P mutation effect. Blood Cells Mol Dis. 2003 May-Jun;30(3):231-7. PMID:12737937
13. ↑ Biasiotto G, Belloli S, Ruggeri G, Zanella I, Gerardi G, Corrado M, Gobbi E, Albertini A, Arosio P. Identification of new mutations of the HFE, hepcidin, and transferrin receptor 2 genes by denaturing HPLC analysis of individuals with biochemical indications of iron overload. Clin Chem. 2003 Dec;49(12):1981-8. PMID:14633868 doi:10.1373/clinchem.2003.023440
14. ↑ Wigg AJ, Harley H, Casey G. Heterozygous recipient and donor HFE mutations associated with a hereditary haemochromatosis phenotype after liver transplantation. Gut. 2003 Mar;52(3):433-5. PMID:12584229
15. ↑ Bento MC, Ribeiro ML, Relvas L. Gene symbol: HFE. Disease: Haemochromatosis. Hum Genet. 2004 Mar;114(4):405. PMID:15046077
16. ↑ Ka C, Le Gac G, Dupradeau FY, Rochette J, Ferec C. The Q283P amino-acid change in HFE leads to structural and functional consequences similar to those described for the mutated 282Y HFE protein. Hum Genet. 2005 Sep;117(5):467-75. Epub 2005 Jun 18. PMID:15965644 doi:10.1007/s00439-005-1307-y
17. ↑ Dupradeau FY, Pissard S, Coulhon MP, Cadet E, Foulon K, Fourcade C, Goossens M, Case DA, Rochette J. An unusual case of hemochromatosis due to a new compound heterozygosity in HFE (p.[Gly43Asp;His63Asp]+[Cys282Tyr]): structural implications with respect to binding with transferrin receptor 1. Hum Mutat. 2008 Jan;29(1):206. PMID:18157833 doi:10.1002/humu.9517
18. ↑ Wani MA, Haynes LD, Kim J, Bronson CL, Chaudhury C, Mohanty S, Waldmann TA, Robinson JM, Anderson CL. Familial hypercatabolic hypoproteinemia caused by deficiency of the neonatal Fc receptor, FcRn, due to a mutant beta2-microglobulin gene. Proc Natl Acad Sci U S A. 2006 Mar 28;103(13):5084-9. Epub 2006 Mar 20. PMID:16549777 doi:10.1073/pnas.0600548103
19. ↑ Gorevic PD, Munoz PC, Casey TT, DiRaimondo CR, Stone WJ, Prelli FC, Rodrigues MM, Poulik MD, Frangione B. Polymerization of intact beta 2-microglobulin in tissue causes amyloidosis in patients on chronic hemodialysis. Proc Natl Acad Sci U S A. 1986 Oct;83(20):7908-12. PMID:3532124
20. ↑ Argiles A, Derancourt J, Jauregui-Adell J, Mion C, Demaille JG. Biochemical characterization of serum and urinary beta 2 microglobulin in end-stage renal disease patients. Nephrol Dial Transplant. 1992;7(11):1106-10. PMID:1336137
21. ↑ Momoi T, Suzuki M, Titani K, Hisanaga S, Ogawa H, Saito A. Amino acid sequence of a modified beta 2-microglobulin in renal failure patient urine and long-term dialysis patient blood. Clin Chim Acta. 1995 May 15;236(2):135-44. PMID:7554280
22. ↑ Cunningham BA, Wang JL, Berggard I, Peterson PA. The complete amino acid sequence of beta 2-microglobulin. Biochemistry. 1973 Nov 20;12(24):4811-22. PMID:4586824
23. ↑ Haag-Weber M, Mai B, Horl WH. Isolation of a granulocyte inhibitory protein from uraemic patients with homology of beta 2-microglobulin. Nephrol Dial Transplant. 1994;9(4):382-8. PMID:8084451
24. ↑ Trinh CH, Smith DP, Kalverda AP, Phillips SE, Radford SE. Crystal structure of monomeric human beta-2-microglobulin reveals clues to its amyloidogenic properties. Proc Natl Acad Sci U S A. 2002 Jul 23;99(15):9771-6. Epub 2002 Jul 15. PMID:12119416 doi:10.1073/pnas.152337399
25. ↑ Stewart-Jones GB, McMichael AJ, Bell JI, Stuart DI, Jones EY. A structural basis for immunodominant human T cell receptor recognition. Nat Immunol. 2003 Jul;4(7):657-63. Epub 2003 Jun 8. PMID:12796775 doi:10.1038/ni942
26. ↑ Kihara M, Chatani E, Iwata K, Yamamoto K, Matsuura T, Nakagawa A, Naiki H, Goto Y. Conformation of amyloid fibrils of beta2-microglobulin probed by tryptophan mutagenesis. J Biol Chem. 2006 Oct 13;281(41):31061-9. Epub 2006 Aug 10. PMID:16901902 doi:10.1074/jbc.M605358200
27. ↑ Eakin CM, Berman AJ, Miranker AD. A native to amyloidogenic transition regulated by a backbone trigger. Nat Struct Mol Biol. 2006 Mar;13(3):202-8. Epub 2006 Feb 19. PMID:16491088 doi:10.1038/nsmb1068
28. ↑ Iwata K, Matsuura T, Sakurai K, Nakagawa A, Goto Y. High-resolution crystal structure of beta2-microglobulin formed at pH 7.0. J Biochem. 2007 Sep;142(3):413-9. Epub 2007 Jul 23. PMID:17646174 doi:10.1093/jb/mvm148
29. ↑ Ricagno S, Colombo M, de Rosa M, Sangiovanni E, Giorgetti S, Raimondi S, Bellotti V, Bolognesi M. DE loop mutations affect beta2-microglobulin stability and amyloid aggregation. Biochem Biophys Res Commun. 2008 Dec 5;377(1):146-50. Epub 2008 Oct 1. PMID:18835253 doi:S0006-291X(08)01866-4
30. ↑ Esposito G, Ricagno S, Corazza A, Rennella E, Gumral D, Mimmi MC, Betto E, Pucillo CE, Fogolari F, Viglino P, Raimondi S, Giorgetti S, Bolognesi B, Merlini G, Stoppini M, Bolognesi M, Bellotti V. The controlling roles of Trp60 and Trp95 in beta2-microglobulin function, folding and amyloid aggregation properties. J Mol Biol. 2008 May 9;378(4):887-97. Epub 2008 Mar 8. PMID:18395224 doi:10.1016/j.jmb.2008.03.002
31. ↑ Ricagno S, Raimondi S, Giorgetti S, Bellotti V, Bolognesi M. Human beta-2 microglobulin W60V mutant structure: Implications for stability and amyloid aggregation. Biochem Biophys Res Commun. 2009 Mar 13;380(3):543-7. Epub 2009 Jan 25. PMID:19284997 doi:10.1016/j.bbrc.2009.01.116
32. ↑ Feder JN, Penny DM, Irrinki A, Lee VK, Lebron JA, Watson N, Tsuchihashi Z, Sigal E, Bjorkman PJ, Schatzman RC. The hemochromatosis gene product complexes with the transferrin receptor and lowers its affinity for ligand binding. Proc Natl Acad Sci U S A. 1998 Feb 17;95(4):1472-7. PMID:9465039
33. ↑ Rothenberger S, Iacopetta BJ, Kuhn LC. Endocytosis of the transferrin receptor requires the cytoplasmic domain but not its phosphorylation site. Cell. 1987 May 8;49(3):423-31. PMID:3568132
34. ↑ Bennett MJ, Lebron JA, Bjorkman PJ. Crystal structure of the hereditary haemochromatosis protein HFE complexed with transferrin receptor. Nature. 2000 Jan 6;403(6765):46-53. PMID:10638746 doi:10.1038/47417