Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0162871 (abdominal aortic aneurysm)
 8,664 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An ubiquitous and conserved proteolytic system regulates the stability of mitochondrial inner membrane proteins. Two AAA proteases with catalytic sites at opposite membrane surfaces form a membrane-integrated quality control system and exert crucial functions during the biogenesis of mitochondria. Their activity is modulated by another membrane-protein complex that is composed of prohibitins. Peptides generated upon proteolysis in the matrix space are transported across the inner membrane by an ATP-binding cassette transporter. The function of these conserved components is discussed in the present review.
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PMID:AAA proteases of mitochondria: quality control of membrane proteins and regulatory functions during mitochondrial biogenesis. 1149 3

Vitamin B(12) (cobalamin) is an essential cofactor of two enzymes, methionine synthase and methylmalonyl-CoA mutase. The conversion of the vitamin to its coenzymes requires a series of biochemical modifications for which several genetic diseases are known, comprising eight complementation groups (cblA through cblH). The objective of this study was to clone the gene responsible for the cblA complementation group thought to represent a mitochondrial cobalamin reductase. Examination of bacterial operons containing genes in close proximity to the gene for methylmalonyl-CoA mutase and searching for orthologous sequences in the human genome yielded potential candidates. A candidate gene was evaluated for deleterious mutations in cblA patient cell lines, which revealed a 4-bp deletion in three cell lines, as well as an 8-bp insertion and point mutations causing a stop codon and an amino acid substitution. These data confirm that the identified gene, MMAA, corresponds to the cblA complementation group. It is located on chromosome 4q31.1-2 and encodes a predicted protein of 418 aa. A Northern blot revealed RNA species of 1.4, 2.6, and 5.5 kb predominating in liver and skeletal muscle. The deduced amino acid sequence reveals a domain structure, which belongs to the AAA ATPase superfamily that encompasses a wide variety of proteins including ATP-binding cassette transporter accessory proteins that bind ATP and GTP. We speculate that we have identified a component of a transporter or an accessory protein that is involved in the translocation of vitamin B(12) into mitochondria.
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PMID:Identification of the gene responsible for the cblA complementation group of vitamin B12-responsive methylmalonic acidemia based on analysis of prokaryotic gene arrangements. 1243 53

The ATP-binding cassette half-transporter Mdl1 from Saccharomyces cerevisiae has been proposed to be involved in the quality control of misassembled respiratory chain complexes by exporting degradation products generated by the m-AAA proteases from the matrix. Direct functional or structural data of the transport complex are, however, not known so far. After screening expression in various hosts, Mdl1 was overexpressed 100-fold to 1% of total mitochondrial membrane protein in S. cerevisiae. Based on detergent screens, Mdl1 was solubilized and purified to homogeneity. Mdl1 showed a high binding affinity for MgATP (Kd = 0.26 microm) and an ATPase activity with a Km of 0.86 mm (Hill coefficient of 0.98) and a turnover rate of 2.6 ATP/s. Mutagenesis of the conserved glutamate downstream of the Walker B motif (E599Q) or the conserved histidine of the H-loop (H631A) abolished ATP hydrolysis, whereas ATP binding was not affected. Mdl1 reconstituted into liposomes showed an ATPase activity similar to the solubilized complex. By single particle electron microscopy, a first three-dimensional structure of the mitochondrial ATP-binding cassette transporter was derived at 2.3-nm resolution, revealing a homodimeric complex in an open conformation.
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PMID:Structural and functional fingerprint of the mitochondrial ATP-binding cassette transporter Mdl1 from Saccharomyces cerevisiae. 1715 Sep 58