6cc9

Structural highlights

Disease

[APOA1_HUMAN] Defects in APOA1 are a cause of high density lipoprotein deficiency type 2 (HDLD2) [MIM:604091]; also known as familial hypoalphalipoproteinemia (FHA). Inheritance is autosomal dominant.^{[1] [2]} Defects in APOA1 are a cause of the low HDL levels observed in high density lipoprotein deficiency type 1 (HDLD1) [MIM:205400]; also known as analphalipoproteinemia or Tangier disease (TGD). HDLD1 is a recessive disorder characterized by the absence of plasma HDL, accumulation of cholesteryl esters, premature coronary artery disease, hepatosplenomegaly, recurrent peripheral neuropathy and progressive muscle wasting and weakness. In HDLD1 patients, ApoA-I fails to associate with HDL probably because of the faulty conversion of pro-ApoA-I molecules into mature chains, either due to a defect in the converting enzyme activity or a specific structural defect in Tangier ApoA-I.^{[3] [4]} Note=A mutation in APOA1 is the cause of amyloid polyneuropathy-nephropathy Iowa type (AMYLIOWA); also known as amyloidosis van Allen type or familial amyloid polyneuropathy type III. AMYLIOWA is a hereditary generalized amyloidosis due to deposition of amyloid mainly constituted by apolipoprotein A1. The clinical picture is dominated by neuropathy in the early stages of the disease and nephropathy late in the course. Death is due in most cases to renal amyloidosis. Severe peptic ulcer disease can occurr in some and hearing loss is frequent. Cataracts is present in several, but vitreous opacities are not observed.^{[5] [6] [7] [8]} Defects in APOA1 are a cause of amyloidosis type 8 (AMYL8) [MIM:105200]; also known as systemic non-neuropathic amyloidosis or Ostertag-type amyloidosis. AMYL8 is a hereditary generalized amyloidosis due to deposition of apolipoprotein A1, fibrinogen and lysozyme amyloids. Viscera are particularly affected. There is no involvement of the nervous system. Clinical features include renal amyloidosis resulting in nephrotic syndrome, arterial hypertension, hepatosplenomegaly, cholestasis, petechial skin rash.^{[9] [10] [11]} [RASK_HUMAN] Defects in KRAS are a cause of acute myelogenous leukemia (AML) [MIM:601626]. AML is a malignant disease in which hematopoietic precursors are arrested in an early stage of development.^[12] Defects in KRAS are a cause of juvenile myelomonocytic leukemia (JMML) [MIM:607785]. JMML is a pediatric myelodysplastic syndrome that constitutes approximately 30% of childhood cases of myelodysplastic syndrome (MDS) and 2% of leukemia. It is characterized by leukocytosis with tissue infiltration and in vitro hypersensitivity of myeloid progenitors to granulocyte-macrophage colony stimulating factor. Defects in KRAS are the cause of Noonan syndrome type 3 (NS3) [MIM:609942]. Noonan syndrome (NS) [MIM:163950] is a disorder characterized by dysmorphic facial features, short stature, hypertelorism, cardiac anomalies, deafness, motor delay, and a bleeding diathesis. It is a genetically heterogeneous and relatively common syndrome, with an estimated incidence of 1 in 1000-2500 live births. Rarely, NS is associated with juvenile myelomonocytic leukemia (JMML). NS3 inheritance is autosomal dominant.^{[13] [14] [15] [16] [17] [18]} Defects in KRAS are a cause of gastric cancer (GASC) [MIM:613659]; also called gastric cancer intestinal or stomach cancer. Gastric cancer is a malignant disease which starts in the stomach, can spread to the esophagus or the small intestine, and can extend through the stomach wall to nearby lymph nodes and organs. It also can metastasize to other parts of the body. The term gastric cancer or gastric carcinoma refers to adenocarcinoma of the stomach that accounts for most of all gastric malignant tumors. Two main histologic types are recognized, diffuse type and intestinal type carcinomas. Diffuse tumors are poorly differentiated infiltrating lesions, resulting in thickening of the stomach. In contrast, intestinal tumors are usually exophytic, often ulcerating, and associated with intestinal metaplasia of the stomach, most often observed in sporadic disease.^{[19] [20] [21]} Note=Defects in KRAS are a cause of pylocytic astrocytoma (PA). Pylocytic astrocytomas are neoplasms of the brain and spinal cord derived from glial cells which vary from histologically benign forms to highly anaplastic and malignant tumors.^[22] Defects in KRAS are a cause of cardiofaciocutaneous syndrome (CFC syndrome) [MIM:115150]; also known as cardio-facio-cutaneous syndrome. CFC syndrome is characterized by a distinctive facial appearance, heart defects and mental retardation. Heart defects include pulmonic stenosis, atrial septal defects and hypertrophic cardiomyopathy. Some affected individuals present with ectodermal abnormalities such as sparse, friable hair, hyperkeratotic skin lesions and a generalized ichthyosis-like condition. Typical facial features are similar to Noonan syndrome. They include high forehead with bitemporal constriction, hypoplastic supraorbital ridges, downslanting palpebral fissures, a depressed nasal bridge, and posteriorly angulated ears with prominent helices. The inheritance of CFC syndrome is autosomal dominant. Note=KRAS mutations are involved in cancer development.

Function

[APOA1_HUMAN] Participates in the reverse transport of cholesterol from tissues to the liver for excretion by promoting cholesterol efflux from tissues and by acting as a cofactor for the lecithin cholesterol acyltransferase (LCAT). As part of the SPAP complex, activates spermatozoa motility.^[23] [RASK_HUMAN] Ras proteins bind GDP/GTP and possess intrinsic GTPase activity.

References

1. ↑ Nakata K, Kobayashi K, Yanagi H, Shimakura Y, Tsuchiya S, Arinami T, Hamaguchi H. Autosomal dominant hypoalphalipoproteinemia due to a completely defective apolipoprotein A-I gene. Biochem Biophys Res Commun. 1993 Oct 29;196(2):950-5. PMID:8240372 doi:http://dx.doi.org/S0006-291X(83)72341-7
2. ↑ Ng DS, Leiter LA, Vezina C, Connelly PW, Hegele RA. Apolipoprotein A-I Q[-2]X causing isolated apolipoprotein A-I deficiency in a family with analphalipoproteinemia. J Clin Invest. 1994 Jan;93(1):223-9. PMID:8282791 doi:http://dx.doi.org/10.1172/JCI116949
3. ↑ Nakata K, Kobayashi K, Yanagi H, Shimakura Y, Tsuchiya S, Arinami T, Hamaguchi H. Autosomal dominant hypoalphalipoproteinemia due to a completely defective apolipoprotein A-I gene. Biochem Biophys Res Commun. 1993 Oct 29;196(2):950-5. PMID:8240372 doi:http://dx.doi.org/S0006-291X(83)72341-7
4. ↑ Ng DS, Leiter LA, Vezina C, Connelly PW, Hegele RA. Apolipoprotein A-I Q[-2]X causing isolated apolipoprotein A-I deficiency in a family with analphalipoproteinemia. J Clin Invest. 1994 Jan;93(1):223-9. PMID:8282791 doi:http://dx.doi.org/10.1172/JCI116949
5. ↑ Nakata K, Kobayashi K, Yanagi H, Shimakura Y, Tsuchiya S, Arinami T, Hamaguchi H. Autosomal dominant hypoalphalipoproteinemia due to a completely defective apolipoprotein A-I gene. Biochem Biophys Res Commun. 1993 Oct 29;196(2):950-5. PMID:8240372 doi:http://dx.doi.org/S0006-291X(83)72341-7
6. ↑ Ng DS, Leiter LA, Vezina C, Connelly PW, Hegele RA. Apolipoprotein A-I Q[-2]X causing isolated apolipoprotein A-I deficiency in a family with analphalipoproteinemia. J Clin Invest. 1994 Jan;93(1):223-9. PMID:8282791 doi:http://dx.doi.org/10.1172/JCI116949
7. ↑ Nichols WC, Dwulet FE, Liepnieks J, Benson MD. Variant apolipoprotein AI as a major constituent of a human hereditary amyloid. Biochem Biophys Res Commun. 1988 Oct 31;156(2):762-8. PMID:3142462
8. ↑ Nichols WC, Gregg RE, Brewer HB Jr, Benson MD. A mutation in apolipoprotein A-I in the Iowa type of familial amyloidotic polyneuropathy. Genomics. 1990 Oct;8(2):318-23. PMID:2123470
9. ↑ Nakata K, Kobayashi K, Yanagi H, Shimakura Y, Tsuchiya S, Arinami T, Hamaguchi H. Autosomal dominant hypoalphalipoproteinemia due to a completely defective apolipoprotein A-I gene. Biochem Biophys Res Commun. 1993 Oct 29;196(2):950-5. PMID:8240372 doi:http://dx.doi.org/S0006-291X(83)72341-7
10. ↑ Ng DS, Leiter LA, Vezina C, Connelly PW, Hegele RA. Apolipoprotein A-I Q[-2]X causing isolated apolipoprotein A-I deficiency in a family with analphalipoproteinemia. J Clin Invest. 1994 Jan;93(1):223-9. PMID:8282791 doi:http://dx.doi.org/10.1172/JCI116949
11. ↑ Soutar AK, Hawkins PN, Vigushin DM, Tennent GA, Booth SE, Hutton T, Nguyen O, Totty NF, Feest TG, Hsuan JJ, et al.. Apolipoprotein AI mutation Arg-60 causes autosomal dominant amyloidosis. Proc Natl Acad Sci U S A. 1992 Aug 15;89(16):7389-93. PMID:1502149
12. ↑ Bollag G, Adler F, elMasry N, McCabe PC, Conner E Jr, Thompson P, McCormick F, Shannon K. Biochemical characterization of a novel KRAS insertion mutation from a human leukemia. J Biol Chem. 1996 Dec 20;271(51):32491-4. PMID:8955068
13. ↑ Carta C, Pantaleoni F, Bocchinfuso G, Stella L, Vasta I, Sarkozy A, Digilio C, Palleschi A, Pizzuti A, Grammatico P, Zampino G, Dallapiccola B, Gelb BD, Tartaglia M. Germline missense mutations affecting KRAS Isoform B are associated with a severe Noonan syndrome phenotype. Am J Hum Genet. 2006 Jul;79(1):129-35. Epub 2006 May 1. PMID:16773572 doi:10.1086/504394
14. ↑ Schubbert S, Zenker M, Rowe SL, Boll S, Klein C, Bollag G, van der Burgt I, Musante L, Kalscheuer V, Wehner LE, Nguyen H, West B, Zhang KY, Sistermans E, Rauch A, Niemeyer CM, Shannon K, Kratz CP. Germline KRAS mutations cause Noonan syndrome. Nat Genet. 2006 Mar;38(3):331-6. Epub 2006 Feb 12. PMID:16474405 doi:ng1748
15. ↑ Bertola DR, Pereira AC, Brasil AS, Albano LM, Kim CA, Krieger JE. Further evidence of genetic heterogeneity in Costello syndrome: involvement of the KRAS gene. J Hum Genet. 2007;52(6):521-6. Epub 2007 Apr 28. PMID:17468812 doi:10.1007/s10038-007-0146-1
16. ↑ Zenker M, Lehmann K, Schulz AL, Barth H, Hansmann D, Koenig R, Korinthenberg R, Kreiss-Nachtsheim M, Meinecke P, Morlot S, Mundlos S, Quante AS, Raskin S, Schnabel D, Wehner LE, Kratz CP, Horn D, Kutsche K. Expansion of the genotypic and phenotypic spectrum in patients with KRAS germline mutations. J Med Genet. 2007 Feb;44(2):131-5. Epub 2006 Oct 20. PMID:17056636 doi:10.1136/jmg.2006.046300
17. ↑ Kratz CP, Zampino G, Kriek M, Kant SG, Leoni C, Pantaleoni F, Oudesluys-Murphy AM, Di Rocco C, Kloska SP, Tartaglia M, Zenker M. Craniosynostosis in patients with Noonan syndrome caused by germline KRAS mutations. Am J Med Genet A. 2009 May;149A(5):1036-40. doi: 10.1002/ajmg.a.32786. PMID:19396835 doi:10.1002/ajmg.a.32786
18. ↑ Gremer L, Merbitz-Zahradnik T, Dvorsky R, Cirstea IC, Kratz CP, Zenker M, Wittinghofer A, Ahmadian MR. Germline KRAS mutations cause aberrant biochemical and physical properties leading to developmental disorders. Hum Mutat. 2011 Jan;32(1):33-43. doi: 10.1002/humu.21377. Epub 2010 Dec 9. PMID:20949621 doi:10.1002/humu.21377
19. ↑ Deng GR, Lu YY, Chen SM, Miao J, Lu GR, Li H, Cai H, Xu XL, E Z, Liu PN. Activated c-Ha-ras oncogene with a guanine to thymine transversion at the twelfth codon in a human stomach cancer cell line. Cancer Res. 1987 Jun 15;47(12):3195-8. PMID:3034404
20. ↑ Lee KH, Lee JS, Suh C, Kim SW, Kim SB, Lee JH, Lee MS, Park MY, Sun HS, Kim SH. Clinicopathologic significance of the K-ras gene codon 12 point mutation in stomach cancer. An analysis of 140 cases. Cancer. 1995 Jun 15;75(12):2794-801. PMID:7773929
21. ↑ Lee SH, Lee JW, Soung YH, Kim HS, Park WS, Kim SY, Lee JH, Park JY, Cho YG, Kim CJ, Nam SW, Kim SH, Lee JY, Yoo NJ. BRAF and KRAS mutations in stomach cancer. Oncogene. 2003 Oct 9;22(44):6942-5. PMID:14534542 doi:10.1038/sj.onc.1206749
22. ↑ Motojima K, Urano T, Nagata Y, Shiku H, Tsurifune T, Kanematsu T. Detection of point mutations in the Kirsten-ras oncogene provides evidence for the multicentricity of pancreatic carcinoma. Ann Surg. 1993 Feb;217(2):138-43. PMID:8439212
23. ↑ Akerlof E, Jornvall H, Slotte H, Pousette A. Identification of apolipoprotein A1 and immunoglobulin as components of a serum complex that mediates activation of human sperm motility. Biochemistry. 1991 Sep 17;30(37):8986-90. PMID:1909888