The outer mitochondrial membranes of all organisms so far examined contain a protein which forms voltage-dependent anion selective channels (VDAC) when incorporated into planar phospholipid membranes. Previous reports have suggested that the yeast (Saccharomyces cerevisiae) outer mitochondrial membrane component responsible for channel formation is a protein of 29,000 daltons which is also the major component of this membrane. In this report, we describe the purification of this 29,000-dalton protein to virtual homogeneity from yeast outer mitochondrial membranes. The purified protein readily incorporates into planar phospholipid membranes to produce ionic channels. Electrophysiological characterization of these channels has demonstrated they have a size, selectivity and voltage dependence similar to VDAC from other organisms. Biochemically, the purified protein has been characterized by determining its amino acid composition and isoelectric point (pI). In addition, we have shown that the purified protein, when reconstituted into liposomes, can bind hexokinase in a glucose-6-phosphate dependent manner, as has been shown for VDAC purified from other sources. Since physiological characterization suggests that the functional parameters of this protein have been conserved, antibodies specific to yeast VDAC have been used to assess antigenic conservation among mitochondrial proteins from a wide number of species. These experiments have shown that yeast VDAC antibodies will recognize single mitochondrial proteins from Drosophila, Dictyostelium and Neurospora of the appropriate molecular weight to be VDAC from these organisms. No reaction was seen to any mitochondrial protein from rat liver, rainbow trout, Paramecium, or mung bean. In addition, yeast VDAC antibodies will recognize a 50-kDa mol wt protein present in tobacco chloroplasts.(ABSTRACT TRUNCATED AT 250 WORDS)
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http://dx.doi.org/10.1007/BF01870622 | DOI Listing |
J Cell Sci
January 2025
Zellbiologie, Universität Bayreuth, 95440 Bayreuth, Germany.
Budding yeast cells multiply by asymmetric cell division. During this process, the cell organelles are transported by myosin motors along the actin cytoskeleton into the growing bud, while at the same time some organelles must be retained in the mother cell. The ordered partitioning of organelles depends on highly regulated binding of motor proteins to cargo membranes.
View Article and Find Full Text PDFNat Cell Biol
January 2025
Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
Mitochondrial protein import through the outer and inner membranes is key to mitochondrial biogenesis. Recent studies have explored how cells respond when import is impaired by a variety of different insults. Here, we developed a mammalian import blocking system using dihydrofolate reductase fused to the N terminus of the inner membrane protein MIC60.
View Article and Find Full Text PDFJ Endocrinol
January 2025
W Miller, Department of Pediatrics, Center for Reproductive Sciences, and Institute for Human Genetics University of California, San Francisco, United Kingdom of Great Britain and Northern Ireland.
Current understanding of the biology, biochemistry and genetics of the steroidogenic acute regulatory protein (StAR) and its deficiency state (congenital lipoid adrenal hyperplasia, lipoid CAH) involves the complex interplay of four areas of study: the acute regulation of steroidogenesis, clinical phenomena in lipoid CAH, the enzymatic conversion of cholesterol to pregnenolone in steroidogenic mitochondria, and the cell biology of StAR. This review traces the origins of these areas of study, describes how they have been woven into an increasingly coherent fabric, and tries to explore some remaining loose ends in this ongoing field of endocrine research. Abundant research from multiple laboratories establishes that StAR is required for the rapid, abundant steroidal responses of the adrenals and gonads, but all steroidogenic cells, especially the placenta, have StAR-independent steroidogenesis, whose basis remains under investigation.
View Article and Find Full Text PDFPoult Sci
December 2024
MOA Key Laboratory of Animal Virology, College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China; Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China. Electronic address:
FEBS Lett
January 2025
Institute of Pharmaceutical Science, King's College London, UK.
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