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  • Articles  (13)
  • Genetics  (7)
  • Peroxisomes  (6)
  • 11
    Electronic Resource
    Electronic Resource
    Immunocytochemical demonstration of the peroxisomal ATPase of yeasts (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 6 (1990), S. 45-51 
    Details
    ISSN: 0749-503X
    Keywords: Yeasts ; peroxisomes ; ATPase ; freeze-fracturing immunocytochemistry ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The presence of an ATpase on yeast peroxisomal membranes was studied by immunological methods. Western blot analysis of purified peroxisomal membranes from several yeasts revealed distinct cross-reaction with specific antibodies against the F1-part or the β-subunit of the mitochondrial ATpase of Saccharomyces cerevisiae. This was not due to mitochondrial contamination as was demonstrated by analytical sucrose gradient centrifugation.Protein A-gold labelling carried out on Lowicryl-embedded methanol-grown Hansenula polymorpha using these antibodies did not result in significant staining. However, when organelles isolated from this yeast were successively incubated with antibodies and protein A-gold prior to embedding, specific labelling was observed on both the peroxisomal membrane and the membrane of damaged mitochondria but not on intact mitochondira. Specific labelling of the peroxisomal membrane was confirmed by freeze-fracture immunocytochemistry. In addition to the peroxisomal membrane, the mitochondrial membrane was also labelled in these experiments. Freeze-fracture immunocytochemistry was also successful for the localization of peroxisomal matrix proteins, e.g. alcohol oxidase and dihydroxyacetone synthase and of mitochondrial membrane proteins, e.g. cytochrome c oxidase.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320060105
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  • 12
    Electronic Resource
    Electronic Resource
    Liposome-mediated introduction of proteins into protoplasts of the yeast Hansenula polymorpha as a possible tool to study peroxisome biogenesis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 6 (1990), S. 99-105 
    Details
    ISSN: 0749-503X
    Keywords: Hansenula polymorpha ; peroxisome biogenesis ; low pH-induced membrane fusion ; alcohol oxidase ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Low pH-induced fusion between liposomes and protoplasts of the yeast Hansenula polymorpha was demonstrated using a fluorescent assay and freeze-etch techniques. By this method foreign proteins could be introduced into the cytosol of the protoplast. For instance, after fusion of glucose oxidase-containing liposomes with protoplasts, activity of this enzyme was demonstrated cytochemically in the cytosol of the resulting protoplasts. Similar results were obtained when ferritin-containing liposomes were used. Incorporation of foreign proteins into liposomes was not a prerequisite for their introduction into the cytosol of protoplasts. In experiments where ferritin was added to protoplast suspensions together with empty liposomes, this protein was also delivered to the protoplast cytosol. However, in the absence of liposomes no uptake of proteins occurred.We tested the potential of this system in our studies on peroxisome biogenesis. Protoplasts of glucose-grown H. polymorpha remained stable for prolonged periods in osmotically stabilized cultivation media. Peroxisomes in such protoplasts were capable of protein import and assembly of matrix proteins as was demonstrated by the 20-fold increase in catalase activity after incubation with methanol or ethanol. However, mature alcohol oxidase purified from H. polymorpha introduced into protoplasts of glucose-grown cells of this organism was not targeted to peroxisomes as demonstrated with (immuno)cytochemical techniques. The enzyme remained present in the cytosol while its activity gradually decreased. Therefore mature alcohol oxidase probably does not expose the right topogenic signal(s) for recognition by its target organelle.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320060203
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  • 13
    Electronic Resource
    Electronic Resource
    The In Vitro permeability of yeast peroxisomal membranes is caused by a 31 kDa integral membrane protein (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 9 (1993), S. 733-742 
    Details
    ISSN: 0749-503X
    Keywords: Yeasts ; peroxisomes ; Hansenula polymorpha ; peroxisomal membrane ; permeability ; membrane protein ; ΔΨ measurements ; pore-forming protein ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A major 31 kDa integral peroxisomal membrane protein (PMP31) of Hansenula polymorpha was purified to homogeneity from isolated peroxisomal membranes by FPLC after solubilization by Triton X-100. Biochemical analysis indicated that this protein, which showed cross-reactivity with antibodies against the 31 kDa porin of the mitochondrial outer membrane of Saccharomyces cerevisiae, had pore-forming properties. Firstly, proteoliposomes composed of asolectin and purified PMP31 showed selective permeability, determined as the [14C]sucrose/[3H]dextran leakage ratios. Furthermore, the generation of a ΔΨ by potassium diffusion gradients was negatively affected by the presence of PMP31 in asolectin liposomes. A similar effect was observed in proteoliposomes containing purified cytochrome c oxidase as a ΔΨ generating system. Control experiments confirmed that the observed leakage is significant and introduced by the incorporation of PMP31 protein. Selective sucrose leakage was abolished in samples pretreated with glutaraldehyde; an identical effect of glutaraldehyde was, however, not observed for the membrane potential measurements.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320090707
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