ABCMdb

ABCG8 p.Arg405His

Predicted by SNAP2:	A: D (91%), C: D (91%), D: D (95%), E: D (95%), F: D (95%), G: D (95%), H: D (95%), I: D (91%), K: D (85%), L: D (91%), M: D (95%), N: D (95%), P: D (95%), Q: D (95%), S: D (95%), T: D (95%), V: D (95%), W: D (95%), Y: D (91%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, S: D, T: D, V: D, W: D, Y: D,

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[hide] Arginine 383 is a crucial residue in ABCG2 biogene... Biochim Biophys Acta. 2009 Jul;1788(7):1434-43. Epub 2009 May 3. Polgar O, Ediriwickrema LS, Robey RW, Sharma A, Hegde RS, Li Y, Xia D, Ward Y, Dean M, Ozvegy-Laczka C, Sarkadi B, Bates SE
Arginine 383 is a crucial residue in ABCG2 biogenesis.
Biochim Biophys Acta. 2009 Jul;1788(7):1434-43. Epub 2009 May 3., [PMID:19406100]

Abstract [show]
ABCG2 is an ATP-binding cassette half-transporter initially identified in multidrug-resistant cancer cell lines and recently suggested to play an important role in pharmacokinetics. Here we report studies of a conserved arginine predicted to localize near the cytoplasmic side of TM1. First, we determined the effect of losing charge and bulk at this position via substitutions with glycine and alanine. The R383G mutant when transfected into HEK cells was not detectable on immunoblot or by functional assay, while the R383A mutant exhibited detectable but significantly decreased levels compared to wild-type, partial retention in the ER and altered glycosylation. Efflux of the ABCG2-substrates mitoxantrone and pheophorbide a was observed. Our experiments suggested rapid degradation of the R383A mutant by the proteasome via a kifunensine-insensitive pathway. Interestingly, overnight treatment of the R383A mutant with mitoxantrone assisted in protein maturation as evidenced by a shift to the N-glycosylated form. The R383A mutant when expressed in insect cells, though detected on the surface, had no measurable ATPase activity. In addition, substitution with the positively charged lysine resulted in significantly decreased protein expression levels in HEK cells, while retaining function. In conclusion, arginine 383 is a crucial residue for ABCG2 biogenesis, where even the most conservative mutations have a large impact.

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197 Interestingly, we noted that an arginine to histidine mutation in the corresponding residue in ABCG8 (R405H) had been reported in a patient with sitosterolemia [41]. Login to comment
261 It will be interesting to discover whether the corresponding R405H mutation in ABCG8 leads to similar effects on protein levels and trafficking as predicted by our data but not yet demonstrated in clinical samples, and if so, whether that mutant can be rescued in part or to any degree by pharmacological chaperones. Login to comment

[hide] Mutations in the human ATP-binding cassette transp... Hum Mutat. 2002 Aug;20(2):151. Heimerl S, Langmann T, Moehle C, Mauerer R, Dean M, Beil FU, von Bergmann K, Schmitz G
Mutations in the human ATP-binding cassette transporters ABCG5 and ABCG8 in sitosterolemia.
Hum Mutat. 2002 Aug;20(2):151., [PMID:12124998]

Abstract [show]
Phytosterolemia or Sitosterolemia is a rare autosomal recessive disorder characterized by highly elevated plasma levels of plant sterols and cholesterol as a consequence of hyperabsorption and impaired biliary secretion of sterols. The disease is caused by mutations in two half size ATP-binding cassette transporters, ABCG5 and ABCG8. We have analyzed the genomic sequence of ABCG5 and ABCG8 in five well-characterized patients with Sitosterolemia. In the first patient we found a heterozygous mutation in exon 8 of the ABCG5 gene leading to a premature termination of the protein (Arg408Ter). This German patient is the first European showing a mutation of the ABCG5 gene. In a second patient we found a novel heterozygous mutation in exon 5 of ABCG8 (c.584T>A; Leu195Gln). Both patients were heterozygous for the identified mutation, but no mutation could be identified on the other chromosome. In three further analyzed patients we found mutations in exons 7, 9 and 11 of the ABCG8 gene, respectively, of which two result in a premature termination signal for translation products. One of these patients was compound heterozygous (Trp361Ter and Arg412Ter), the other was homozygous for Trp361Ter. The third patient was homozygous for an amino acid exchange (Gly574Arg). In conclusion this report describes one novel mutation affecting a highly conserved amino acid and two previously identified mutations in the ABCG8 gene. In addition, we identified for the first time a mutation in the ABCG5 gene of a European Sitosterolemia patient.

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77 C Y658stop R121stop R164stop Q172stop R184H L195Q P231T G574R G574E L572P L596R N ABC B S AA R263Q E146Q R405H R543S W536stop R412stop W361stop C R419P R419H R408stop R398H N437K R550S R243stop N ABCG5 ABCG8 S B A IVS1 -2A>G Del547C>191stop L501P L596R 1568_1572delTCTTT 1798_1800delTTC Del Exon 3 C336-337insA 201 * Signature 250 ABCG1 Q..EKDEG.R REMVKEILTA L GLLSCANTR TGS.... .LS GGQR KRLAIA ABCG2 ATTMTNHE.K NERINRVIEE L GLDKVADSK VGTQFIR GVS GGER KRTSIG ABCG4 S..EKQEV.K KELVTEILTA L GLMSCSHTR TAL.... .LS GGQR KRLAIA ABCG5 R..RGNPGSF QKKVEAVMAE L SLSHVADRL IGNYSLG GIS TGER RRVSIA ABCG8 PRTFSQAQ.R DKRVEDVIAE L RLRQCADTR VGNMYVR GLS GGER RRVSIG Figure 2: Alignment of the human ABC transporters G1, G2, G4, G5 and G8. The amino acid change Leu195Gln in ABCG8 found in patient 2 is located intracellularly between the Walker A and the Signature C-motif. Login to comment

[hide] Two genes that map to the STSL locus cause sitoste... Am J Hum Genet. 2001 Aug;69(2):278-90. Epub 2001 Jul 9. Lu K, Lee MH, Hazard S, Brooks-Wilson A, Hidaka H, Kojima H, Ose L, Stalenhoef AF, Mietinnen T, Bjorkhem I, Bruckert E, Pandya A, Brewer HB Jr, Salen G, Dean M, Srivastava A, Patel SB
Two genes that map to the STSL locus cause sitosterolemia: genomic structure and spectrum of mutations involving sterolin-1 and sterolin-2, encoded by ABCG5 and ABCG8, respectively.
Am J Hum Genet. 2001 Aug;69(2):278-90. Epub 2001 Jul 9., [PMID:11452359]

Abstract [show]
Sitosterolemia is a rare autosomal recessive disorder characterized by (a) intestinal hyperabsorption of all sterols, including cholesterol and plant and shellfish sterols, and (b) impaired ability to excrete sterols into bile. Patients with this disease have expanded body pools of cholesterol and very elevated plasma plant-sterol species and frequently develop tendon and tuberous xanthomas, accelerated atherosclerosis, and premature coronary artery disease. In previous studies, we have mapped the STSL locus to human chromosome 2p21. Recently, we reported that a novel member of the ABC-transporter family, named "sterolin-1" and encoded by ABCG5, is mutated in 9 unrelated families with sitosterolemia; in the remaining 25 families, no mutations in sterolin-1 could be identified. We identified another ABC transporter, located <400 bp upstream of sterolin-1, in the opposite orientation. Mutational analyses revealed that this highly homologous protein, termed "sterolin-2" and encoded by ABCG8, is mutated in the remaining pedigrees. Thus, two highly homologous genes, located in a head-to-head configuration on chromosome 2p21, are involved as causes of sitosterolemia. These studies indicate that both sterolin-1 and sterolin-2 are indispensable for the regulation of sterol absorption and excretion. Identification of sterolin-1 and sterolin-2 as critical players in the regulation of dietary-sterol absorption and excretion identifies a new pathway of sterol transport.

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134 A human full- Table 2 Compilation of Mutations in ABCG5 and ABCG8 PATIENT (NATIONALITY/ETHNICITY) MUTATIONS IN ABCG5a ABCG8b 4 (U.S./white) Trp361X (1173GrA) / Arg412X (1324CrT) 9 (U.S./white) Arg543Ser (1719GrT) / Gln172X (604CrT) 56c (U.S./white) Trp361X (1173GrA) / Tyr658X (2064CrG) 60 (U.S./white) Trp361X (1173GrA) / IVS1 -2 ArG 90c (U.S./white) Trp361X (1173GrA) / Trp361X (1173GrA) 94 (U.S./white) Trp361X (1173GrA) / Arg184His (641GrA) 120 (U.S./white) Trp361X (1173GrA) / Leu501Pro (1592TrC) 125 (U.S./white) Trp361X (1173GrA) / Trp361X (1173GrA) 128 (U.S./white) Leu596Arg (1877TrG) / IVS1 -2 ArG 172 (U.S./white) Trp361X (1173GrA) / Tyr658Stop (2064CrG) 166c (U.S./white) Trp361X (1173GrA) / Arg412X (1324CrT) 32 (SA/white) Arg121X (451CrT) / Arg121X (451CrT) 98 (Dutch/white) Trp361X (1173GrA) / Gly574Glu (1811GrA) 102c,d (U.S./white) Trp361X (1173GrA) / … 84c (U.S./Amish-Mennonite) Gly574Arg (1810GrA) / Gly574Arg (1810GrA) 108c (U.S./Amish-Mennonite) Gly574Arg (1810GrA) / Gly574Arg (1810GrA) 135 (Columbian/white) Trp536X (1698GrA) / Trp536X (1698GrA) 175 (French) 1798_1800delTTC / Arg405His (1304GrA) 20 (Finnish) Trp361X (1173GrA) / Trp361X (1173GrA) 154 (Finnish) Trp361X (1173GrA) / … 116 (Norwegian) Trp361X (1173GrA) / Trp361X (1173GrA) 163 (Swedish) Trp361X (1173GrA) / Leu572Pro (1805TrC) 15 (U.S./white) 1568_1572delTCTTT / IVS1 -2 ArG 143 (SA/Asian) Arg164X (580CrT) / Arg121X (451CrT) 25 (SA/Asian) Arg243X (876CrT) / Arg243X (876CrT) 40 (Japanese) Arg419His (1396GrA) / Arg419His (1396GrA) 46 (Japanese) Arg389His (1306GrA) / Arg389His (1306GrA) 63 (Japanese) del exon 3 / del exon 3 113 (Japanese) Arg389His (1306GrA) / Arg389His (1306GrA) 132 (Japanese) Arg419His (1396GrC) / Arg550Ser (1790ArC) 140 (Japanese) Arg408X (1362CrT) / Arg408X (1362CrT) 146 (Japanese) Arg389His (1306GrA) / Arg389His (1306GrA) 157 (U.S./white) Arg419Pro (1396GrC) / Arg419Pro (1396GrC) 149 (African American) Glu146Gln (576GrC) / … 1c,e (German/Swiss) Trp361X / Trp361X 2c,e (U.S./Amish) Gly574Arg / Gly574Arg 3c,e (U.S./white) Trp361X / Tyr658X 5c,d (U.S./white) Trp361X / Arg412X 6c,e (U.S./white) Leu596Arg / … 7d (U.S./Hispanic) Arg412X / del547Cr191X 8c,e (New Zealand/white) Trp361X / … 4e (Chinese) Arg263Gln / Pro231Thr 9e (Chinese) Arg408X / … a GenBank accession number AF312715. Login to comment
146 of Alleles Frequency Restriction-Enzyme Recognition ABCG5: Glu146Gln 1 .05 Gain of AlwNI Arg243X 2 .10 Gain of AlwNI Arg389His 6 .30 Loss of BstUI Arg408X 3 .15 Loss of AvaI Arg419Pro 2 .10 Loss of BstUI Arg419His 3 .15 Loss of BstUI del exon 3 2 .10 … Arg550Ser 1 .05 … Total 20 ABCG8: Arg121X 3 .061 Gain of DdeI Arg164stop 1 .020 … Gln172X 1 .020 Gain of BfaI Arg184His 1 .020 Gain of NalIII Pro231Thr 1 .020 Loss of NlaIV Arg263Gln 1 .020 Gain of AluI Trp361X 19 .39 26; Arg405His 1 .020 … Arg412X 3 .061 Gain of DdeI Leu501Pro 1 .020 Loss of AluI Trp536X 2 .041 Gain of AhdI Arg543Ser 1 .020 … Leu572Pro 1 .020 Gain of FauI Gly574Glu 1 .020 Loss of MspI Gly574Arg 4 .082 Loss of MspI Leu596Arg 1 .020 Gain of MspI Tyr658X 2 .041 Gain of SfcI IVS1 -2ArG 3 .061 Gain of BtgI 1798_1800delTTC 1 .020 … 1568_1572delTCTTT 1 .020 … Total 49 Mutations of Sterolin-2/ABCG8 as the Cause of Sitosterolemia Information on the exon/intron boundaries was used to screen probands, including those known to be mutated for sterolin-1, and to compare them to normal controls. Login to comment

[hide] Premature atherosclerosis is not systematic in phy... Atherosclerosis. 2014 May;234(1):162-8. doi: 10.1016/j.atherosclerosis.2014.02.030. Epub 2014 Mar 11. Hansel B, Carrie A, Brun-Druc N, Leclert G, Chantepie S, Coiffard AS, Kahn JF, Chapman MJ, Bruckert E
Premature atherosclerosis is not systematic in phytosterolemic patients: severe hypercholesterolemia as a confounding factor in five subjects.
Atherosclerosis. 2014 May;234(1):162-8. doi: 10.1016/j.atherosclerosis.2014.02.030. Epub 2014 Mar 11., [PMID:24657386]

Abstract [show]
OBJECTIVE: Phytosterolemia is a rare autosomal recessive disorder characterized by dramatically elevated circulating levels of plant sterols (PS). Phytosterolemia is believed to be responsible for severe premature atherosclerosis. The clinical, biological and molecular genetic features of 5 patients with phytosterolemia and transient severe hypercholesterolemia challenge this hypothesis. METHODS: Our patients were referred for suspected homozygous familial hypercholesterolemia. Despite the phenotype, this diagnosis was invalidated and phytosterolemia was confirmed by the identification of mutations in the ABCG5/ABCG8 transporter complex. Plasma PS were analyzed with a mass spectrometric-gas chromatographic procedure. Vascular status was assessed with carotid ultrasonography and completed (for 4 of the 5 patients) with femoral ultrasonography; additional examinations of cardiovascular status included a stress test, determination of coronary calcium score, echocardiography, non-invasive assessment of endothelium-dependent dilatation and coronarography. RESULTS: The 5 patients displayed markedly elevated levels of both beta-sitosterol and campesterol (15-30 fold higher than normal values). However, none displayed significant signs of infraclinical premature atherosclerosis (respectively at the ages of 32, 27, 29, 11 and 11 years). All patients were characterized by very high levels of total (>450 mg/dl) and LDL-cholesterol (>350 mg/dl) at diagnosis which decreased markedly on dietary intervention alone. Treatment with cholestyramine or Ezetimibe +/- atorvastatin normalized cholesterol levels, although plasma PS concentrations remained elevated. CONCLUSION: The clinical and biological characteristics of our patients, considered together with reports of cases which equally lack CVD, support the contention that the premature atherosclerosis associated with phytosterolemia in some patients may be due at least in part to mechanisms independent of elevated circulating phytosterol levels.

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111 Propositus Age (years) Age at diagnosis (years) Family history of CHD History of CVD Cutaneous xanthomas Tendinous xanthoma Thrombocytopenia/ anemia Liver enzymes Genetics: mutated gene mutation allele 1 mutation allele 2 Major CV risk factors Patient 1 32 18 No No Yes Yes Yes/no N ABCG8 p.Arg405His p.Phe570del High BP: N Smoking: N Diabetes: N Patient 2 27 13 No No No Yes No/no N ABCG8 p.Arg405His p.Phe570del High BP: N Smoking: N Diabetes: N Patient 3 33 4 No No Yes Yes Yes/no Unexplained increase in transaminases during 2 years ABCG8 p.Asp160Thr p.Arg263Gln High BP: N Smoking: N Diabetes: N Patient 4 17 9 Yesa No Yes Yes No/no N ABCG8 p.Arg164* p.Tyr492* High BP: N Smoking: N Diabetes: N Patient 5 19 10 No No Yes Yes No/no N ABCG8 p.Arg405His p.Trp361* High BP: N Smoking: N Diabetes: N a Myocardial Infarction mother 47 years. Login to comment