Human microsomal triglyceride transfer protein large subunit gene structure

Sharp, Daru; Ricci, Beverly; Kienzle, Bernadette; Lin, Marie C.; Wetterau, John R.

doi:10.1021/bi00197a005

Cited by 43 publications

(26 citation statements)

References 28 publications

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“…2) of the smaller bands indicated a deletion of 107 nucleotides from 1237 to 1344. This corresponds to a perfect in-frame deletion of exon 10 of the MTP 97-kDa subunit gene (16). This yields an internal deletion of 36 amino acids stretching from residue 413 to 448, explaining the difference in electrophoretic mobility between this form of the protein and the wild type form, as shown in Fig.…”

Section: Resultsmentioning

confidence: 89%

A Novel Abetalipoproteinemia Genotype

Rehberg

Samson-Bouma

Kienzle

et al. 1996

Journal of Biological Chemistry

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The microsomal triglyceride transfer protein (MTP) is a heterodimer composed of the ubiquitous multifunctional protein, protein disulfide isomerase, and a unique 97-kDa subunit. Mutations that lead to the absence of a functional 97-kDa subunit cause abetalipoproteinemia, an autosomal recessive disease characterized by a defect in the assembly and secretion of apolipoprotein B (apoB) containing lipoproteins. Previous studies of abetalipoproteinemic patient, C.L., showed that the 97-kDa subunit was undetectable. In this report, [35 S]methionine labeling showed that this tissue was capable of synthesizing the 97-kDa MTP subunit. Electrophoretic analysis showed two bands, one with a molecular mass of the wild type 97-kDa subunit and the other with a slightly lower molecular weight. Sequence analysis of cDNAs from additional intestinal biopsies showed this patient to be a compound heterozygote. One allele contained a perfect in-frame deletion of exon 10, explaining the lower molecular weight band. cDNAs of the second allele were found to contain 3 missense mutations: His 297 3 Gln, Asp 384 3 Ala, and Arg 540 3 His. Transient expression of each mutant showed that only the Arg 540 3 His mutant was non-functional based upon its inability to reconstitute apoB secretion in a cell culture system. The other amino acid changes are silent polymorphisms. High level coexpression in a baculovirus system of the wild type 97-kDa subunit or the Arg 540 3 His mutant along with human protein disulfide isomerase showed that the wild type was capable of forming an active MTP complex while the mutant was not. Biochemical analysis of lysates from these cells showed that the Arg to His conversion interrupted the interaction between the 97-kDa subunit and protein disulfide isomerase. Replacement of Arg 540 with a lysine residue maintained the ability of the 97-kDa subunit to complex with protein disulfide isomerase and form the active MTP holoprotein. These results indicate that a positively charged amino acid at position 540 in the 97-kDa subunit is critical for the productive association with protein disulfide isomerase. Of the 13 mutant MTP 97-kDa subunit alleles described to date, this is the first encoding a missense mutation. The microsomal triglyceride transfer protein (MTP)1 is an endoplasmic reticulum resident protein that catalyzes the transfer of lipids between phospholipid surfaces. Although MTP can transfer most classes of lipids, it shows a distinct preference for triglyceride and cholesteryl esters. MTP is a heterodimer composed of the multifunctional protein, protein disulfide isomerase (PDI) and a unique large subunit of 97 kDa (1). PDI is a ubiquitous protein found at high levels in many different tissues (2). The 97-kDa subunit of MTP is expressed primarily in hepatocytes and intestinal enterocytes (3). Thus, the active MTP complex is found predominantly in the liver and small intestine. The subcellular localization, tissue distribution, and activity of MTP all suggest a role for this protein in the assembly and secretio...

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Section: Resultsmentioning

confidence: 89%

A Novel Abetalipoproteinemia Genotype

Rehberg

Samson-Bouma

Kienzle

et al. 1996

Journal of Biological Chemistry

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“…From the published sequences of the MTP gene [11], 4640 bp, including the 5 -flanking, coding, intronic (exon-intron boundaries), and 3 -flanking regions were directly sequenced (ABI PRISM 377, PerkinElmer, Rodgau-Jügesheim, Germany) in 11 individuals with the lowest apoB (0.54-0.67 g/L) and 14 with the highest apoB levels (2.56-4.76 g/L) from the ECTIM Study. Specific amplification protocols can be obtained online (http://genecanvas.ecgene.…”

Section: Direct Sequencing Of the Microsomal Triglyceride Transfer Prmentioning

confidence: 99%

Osteopontin gene variation and cardio/cerebrovascular disease phenotypes

Schmidt-Petersen

Brand²,

Telgmann

et al. 2009

Atherosclerosis

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a b s t r a c tWe aimed at associating common osteopontin (OPN) gene variants with cardiovascular disease phenotypes.We scanned the OPN gene in 190 chromosomes from myocardial infarction (MI) patients and identified five variants in the promoter, three synonymous and one non-synonymous variant. All variants were investigated in case-control studies for MI (ECTIM: 990 cases, 900 controls) and brain infarction (BI) (GÉNIC: 466 cases, 444 controls). Promoter variants were functionally analyzed by bandshift assays, the coding D147D [T/C] by Western blot. Allele D147D C was independently and significantly associated with lower apoB levels (P = 0.044 [ECTIM] P = 0.03 [GENIC]), its allele frequency was significantly lower in patients with BI compared to controls (OR [95% CI] 0.39 [0.20-0.74], P = 0.004), and C allele carriers had a significantly lower frequency of presence of carotid plaques (P = 0.02). Bandshifts with HepG2 and Ea.hy926 nuclear proteins did not reveal any functionality of promoter variants, whereas the OPN-441C-containing construct resulted in reduced OPN protein expression in Western blots, complying with its potential protective effect on the phenotypes studied.We here provide evidence that a portion of the OPN locus is likely to associate with cardiovascular disease-related phenotypes. However, further experiments are warranted to clarify the functional role of OPN variants.

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“…PCR was used to amplify exon 10 and adjacent regions using a pair of primers based on published MTP gene sequences. 6 For polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis, a fragment of the junction of intron 9 and exon 10 was amplified by PCR using an intron 9 forward primer, 5Ј-AGAATTCCCTGTACCACAGGT-3Ј, and a mismatch reverse primer of 5Ј-CCAATAGAACCTTTGAACTgACT-3Ј. The 250 base pair fragment was digested with Hinf I, loaded on to a 10% acrylamide gel for electrophoresis, and visualized with ethidium bromide.…”

Section: Mutation Analysismentioning

confidence: 99%

Abetalipoproteinemia Caused by Maternal Isodisomy of Chromosome 4q Containing an Intron 9 Splice Acceptor Mutation in the Microsomal Triglyceride Transfer Protein Gene

Yang

Inazu

Yagi

et al. 1999

ATVB

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Abstract-Uniparental disomy (UPD), a rare inheritance of 2 copies of a single chromosome homolog or a region of a chromosome from one parent, can result in various autosomal recessive diseases. Abetalipoproteinemia (ABL) is a rare autosomal recessive deficiency of apoB-containing lipoproteins caused by a microsomal triglyceride transfer protein (MTP) deficiency. In this study, we describe a patient with ABL inherited as a homozygous intron 9 splice acceptor G(Ϫ1)-to-A mutation of the transfer protein gene. This mutation alters the splicing of the mRNA, resulting in a 36 amino acids, in-frame deletion of sequence encoded by exon 10. We analyzed chromosome 4, including MTP gene (4q22-24), using short tandem repeat markers. The proband has only his mother's genes in chromosome 4q spanning a 150-centimorgan region; ie, segmental maternal isodisomy 4q21-35, probably due to mitotic recombination. Nonpaternity between the proband and his father was excluded using 6 polymorphic markers from different chromosomes (paternity probability, 0.999). Maternal isodisomy (maternal UPD 4q) was the basis for homozygosity of the MTP gene mutation in this patient. (Arterioscler Thromb Vasc Biol. 1999;19

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Human microsomal triglyceride transfer protein large subunit gene structure

Cited by 43 publications

References 28 publications

A Novel Abetalipoproteinemia Genotype

A Novel Abetalipoproteinemia Genotype

Osteopontin gene variation and cardio/cerebrovascular disease phenotypes

Abetalipoproteinemia Caused by Maternal Isodisomy of Chromosome 4q Containing an Intron 9 Splice Acceptor Mutation in the Microsomal Triglyceride Transfer Protein Gene

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