Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.5.1.3 (dihydrofolate reductase)
 5,819 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Subunit IV of yeast cytochrome c oxidase is encoded by a nuclear gene, synthesized in the cytosol as a precursor with a transient amino-terminal extension of 25 amino acids, and imported into the mitochondria. By gene fusion, we have attached the amino-terminal 53 amino acids of the subunit IV precursor to the amino terminus of the mouse cytosolic enzyme dihydrofolate reductase. When the resulting fusion protein was synthesized in a transcription-translation system and then incubated with energized yeast mitochondria, it was imported into the mitochondrial matrix space and processed to a shorter form by the chelator-sensitive matrix protease. No evidence was obtained that the fusion protein became stuck across one of the two mitochondrial membranes. Thus, a non-mitochondrial protein can be transported into the mitochondrial matrix if it is fitted with a mitochondrial targeting sequence.
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PMID:The amino-terminal region of an imported mitochondrial precursor polypeptide can direct cytoplasmic dihydrofolate reductase into the mitochondrial matrix. 609 67

Cytochrome c oxidase subunit II (COXII) in yeast mitochondria is synthesized as a precursor (preCOXII) and is sorted across the inner membrane, whereby both N and C termini become exposed to the intermembrane space. We describe here how this process can be experimentally dissected into a number of distinct stages. Our results demonstrate that the translation of COXII is not obligatorily coupled to translocation. Insertion into the inner membrane and export of the N- and C-terminal domains require an energized inner membrane. The export of COXII is independent of both maturation by the Imp1p protease and assembly into the cytochrome c oxidase complex. When linked to a mitochondrial matrix-targeting sequence, the N-terminal portion of preCOXII (fused to mouse dihydrofolate reductase) can be imported into the mitochondrial matrix. Following accumulation in the matrix, this chimeric protein can become exported across the inner membrane, delivering the N terminus into the intermembrane space where it undergoes processing by the Imp1p protease. This export process displays a number of similarities to bacterial protein export and supports the view that the principles of sorting are conserved from prokaryotes to eukaryotic organelles.
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PMID:Topogenesis of cytochrome oxidase subunit II. Mechanisms of protein export from the mitochondrial matrix. 759 59