scholarly journals The peroxisomes strike BAK: Regulation of peroxisome integrity by the Bcl-2 family

2017 ◽  
Vol 216 (3) ◽  
pp. 547-549 ◽  
Author(s):  
Jerry Edward Chipuk ◽  
Mark P.A. Luna-Vargas
Keyword(s):  
Membrane Integrity ◽  
Mitochondrial Pathway ◽  
Matrix Proteins ◽  
Cell Biol ◽  
Peroxisome Membrane

Within the mitochondrial pathway of apoptosis, VDAC2 controls both the localization and proapoptotic activity of BAK. In this issue, Hosoi et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201605002) find that loss of VDAC2 diverts BAK into peroxisome membranes, revealing the ability of BAK to control peroxisome membrane integrity and the release of soluble peroxisomal matrix proteins.

Biochemical Characterization of Chlorophyll-Free Mitochondria From Pea Leaves

1985 ◽  
Vol 12 (3) ◽  
pp. 219 ◽  
Author(s):  
DA Day ◽  
M Neuburger ◽  
R Douce
Keyword(s):  
Biochemical Characterization ◽  
Membrane Integrity ◽  
Phospholipid Composition ◽  
Respiratory Control ◽  
Matrix Proteins ◽  
Green Leaf ◽  
Protein Ratio ◽  
Linear Gradient ◽  
The Matrix

Mitochondria from pea leaves were purified by centrifugation on a self-generated Percoll gradient which contained a linear gradient of polyvinylpyrrolidone-25 (0-10%, w/v). The chlorophyll content of the purified mitochondria was less than 1 �g per mg protein. All substrates were rapidly oxidized by these mitochondria, the rate of glycine oxidation being between 200 and 300 nmol O2 min-1 mg-1 protein, depending on the age of the leaves used. These rates did not vary significantly over a period of 20 h, provided NAD+ was supplied exogenously, when the mitochondria were stored on ice. Respiratory control, ADP/O ratios and outer membrane integrity (always more than 95%) were also maintained during storage. The phospholipid composition of the membranes from the leaf mitochondria was virtually identical to that of mitochondria from non-photosynthetic tissues although their lipid to protein ratio was slightly lower. The polypeptide pattern of the membranes from green leaf mitochondria and those from etiolated leaves and hypocotyls were also similar, but marked differences were observed between the matrix proteins from the different tissues. In particular, intensely stained bands at 94, 51,41 and 15.5 kDa which were present in the matrix of green leaf mitochondria were missing or present in much smaller quantities in the non-photosynthetic tissues. This difference was correlated with the ability of the mitochondria to oxidize glycine, suggesting that the four polypeptides may be associated with the glycine decarboxylase complex.

scholarly journals Pex13p is an SH3 protein of the peroxisome membrane and a docking factor for the predominantly cytoplasmic PTs1 receptor.

1996 ◽  
Vol 135 (1) ◽  
pp. 85-95 ◽  
Author(s):  
S J Gould ◽  
J E Kalish ◽  
J C Morrell ◽  
J Bjorkman ◽  
A J Urquhart ◽  
...  
Keyword(s):  
Steady State ◽  
Matrix Proteins ◽  
Cytoplasmic Protein ◽  
Peroxisomal Membrane ◽  
Peroxisomal Targeting ◽  
Targeting Signal ◽  
Peroxisome Membrane ◽  
Peroxisomal Targeting Signal

Import of newly synthesized PTS1 proteins into the peroxisome requires the PTS1 receptor (Pex5p), a predominantly cytoplasmic protein that cycles between the cytoplasm and peroxisome. We have identified Pex13p, a novel integral peroxisomal membrane from both yeast and humans that binds the PTS1 receptor via a cytoplasmically oriented SH3 domain. Although only a small amount of Pex5p is bound to peroxisomes at steady state (< 5%), loss of Pex13p further reduces the amount of peroxisome-associated Pex5p by approximately 40-fold. Furthermore, loss of Pex13p eliminates import of peroxisomal matrix proteins that contain either the type-1 or type-2 peroxisomal targeting signal but does not affect targeting and insertion of integral peroxisomal membrane proteins. We conclude that Pex13p functions as a docking factor for the predominantly cytoplasmic PTS1 receptor.

scholarly journals Multiple Distinct Targeting Signals in Integral Peroxisomal Membrane Proteins

2001 ◽  
Vol 153 (6) ◽  
pp. 1141-1150 ◽  
Author(s):  
Jacob M. Jones ◽  
James C. Morrell ◽  
Stephen J. Gould
Keyword(s):  
Membrane Proteins ◽  
Matrix Proteins ◽  
Membrane Biogenesis ◽  
Peroxisomal Membrane ◽  
Interesting Possibility ◽  
Peroxisomal Targeting ◽  
Targeting Signal ◽  
Targeting Signals ◽  
Peroxisome Membrane ◽  
Metabolite Transporter

Peroxisomal proteins are synthesized on free polysomes and then transported from the cytoplasm to peroxisomes. This process is mediated by two short well-defined targeting signals in peroxisomal matrix proteins, but a well-defined targeting signal has not yet been described for peroxisomal membrane proteins (PMPs). One assumption in virtually all prior studies of PMP targeting is that a given protein contains one, and only one, distinct targeting signal. Here, we show that the metabolite transporter PMP34, an integral PMP, contains at least two nonoverlapping sets of targeting information, either of which is sufficient for insertion into the peroxisome membrane. We also show that another integral PMP, the peroxin PEX13, also contains two independent sets of peroxisomal targeting information. These results challenge a major assumption of most PMP targeting studies. In addition, we demonstrate that PEX19, a factor required for peroxisomal membrane biogenesis, interacts with the two minimal targeting regions of PMP34. Together, these results raise the interesting possibility that PMP import may require novel mechanisms to ensure the solubility of integral PMPs before their insertion in the peroxisome membrane, and that PEX19 may play a central role in this process.

scholarly journals Peroxisome biogenesis and positioning

2010 ◽  
Vol 38 (3) ◽  
pp. 807-816 ◽  
Author(s):  
Alison Baker ◽  
Imogen A. Sparkes ◽  
Laura-Anne Brown ◽  
Catherine O'Leary-Steele ◽  
Stuart L. Warriner
Keyword(s):  
Endoplasmic Reticulum ◽  
Degradation Pathway ◽  
Matrix Proteins ◽  
Peroxisome Biogenesis ◽  
Environmental Signals ◽  
Targeting Signal ◽  
Membrane Bound ◽  
Plant Life Cycle ◽  
Peroxisome Membrane

Plant peroxisomes are extremely dynamic, moving and undergoing changes of shape in response to metabolic and environmental signals. Matrix proteins are imported via one of two import pathways, depending on the targeting signal within the protein. Each pathway has a specific receptor but utilizes common membrane-bound translocation machinery. Current models invoke receptor recycling, which may involve cycles of ubiquitination. Some components of the import machinery may also play a role in proteolytic turnover of matrix proteins, prompting parallels with the endoplasmic-reticulum-associated degradation pathway. Peroxisome membrane proteins, some of which are imported post-translationally, others of which may traffic to peroxisomes via the endoplasmic reticulum, use distinct proteinaceous machinery. The isolation of mutants defective in peroxisome biogenesis has served to emphasize the important role of peroxisomes at all stages of the plant life cycle.

scholarly journals Pharmacological inhibition of catalase induces peroxisome leakage and suppression of LPS induced inflammatory response in Raw 264.7 cell

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0245799
Author(s):  
Yizhu Mu ◽  
Yunash Maharjan ◽  
Raghbendra Kumar Dutta ◽  
Xiaofan Wei ◽  
Jin Hwi Kim ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Ubiquitin Proteasome System ◽  
Matrix Proteins ◽  
Oxygen Species ◽  
Selective Degradation ◽  
Mediators Of Inflammation ◽  
Ubiquitin Proteasome ◽  
Inflammation Resolution ◽  
Peroxisome Membrane

Peroxisomes are metabolically active organelles which are known to exert anti-inflammatory effects especially associated with the synthesis of mediators of inflammation resolution. However, the role of catalase and effects of peroxisome derived reactive oxygen species (ROS) caused by lipid peroxidation through 4-hydroxy-2-nonenal (4-HNE) on lipopolysaccharide (LPS) mediated inflammatory pathway are largely unknown. Here, we show that inhibition of catalase by 3-aminotriazole (3-AT) results in the generation of peroxisomal ROS, which contribute to leaky peroxisomes in RAW264.7 cells. Leaky peroxisomes cause the release of matrix proteins to the cytosol, which are degraded by ubiquitin proteasome system. Furthermore, 3-AT promotes the formation of 4HNE-IκBα adduct which directly interferes with LPS induced NF-κB activation. Even though, a selective degradation of peroxisome matrix proteins and formation of 4HNE- IκBα adduct are not directly related with each other, both of them are could be the consequences of lipid peroxidation occurring at the peroxisome membrane.

scholarly journals pHocal adhesion kinase regulation is on a FERM foundation

2013 ◽  
Vol 202 (6) ◽  
pp. 833-836
Author(s):  
Christine Lawson ◽  
David D. Schlaepfer
Keyword(s):  
Tumor Cells ◽  
Intracellular Ph ◽  
Focal Adhesion ◽  
Receptor Binding ◽  
Matrix Proteins ◽  
Integrin Receptor ◽  
Kinase Regulation ◽  
Cell Biol ◽  
Focal Adhesion Turnover

Increases in intracellular pH (pHi) occur upon integrin receptor binding to matrix proteins and in tumor cells. In this issue, Choi et al. (2013. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201308034) show that pHi increase activates FAK by causing deprotonation of histidine 58 in its FERM (band 4.1, ezrin, radixin, moesin) homology domain, which exposes a region important for FAK autophosphorylation. This model of FAK activation could contribute to motility of tumor cells by promoting focal adhesion turnover.

scholarly journals Two AAA Family Peroxins, PpPex1p and PpPex6p, Interact with Each Other in an ATP-Dependent Manner and Are Associated with Different Subcellular Membranous Structures Distinct from Peroxisomes

1998 ◽  
Vol 18 (2) ◽  
pp. 936-943 ◽  
Author(s):  
Klaas Nico Faber ◽  
John A. Heyman ◽  
Suresh Subramani
Keyword(s):  
Subcellular Fractionation ◽  
Matrix Proteins ◽  
Temperature Sensitive ◽  
Dependent Manner ◽  
Peroxisome Biogenesis ◽  
Yeast Two Hybrid System ◽  
Cell Biol ◽  
Sensitive Allele ◽  
Two Hybrid

ABSTRACT Two peroxins of the AAA family, PpPex1p and PpPex6p, are required for peroxisome biogenesis in the yeast Pichia pastoris. Cells from the corresponding deletion strains (PpΔpex1and PpΔpex6) contain only small vesicular remnants of peroxisomes, the bulk of peroxisomal matrix proteins is mislocalized to the cytosol, and these cells cannot grow in peroxisome-requiring media (J. A. Heyman, E. Monosov, and S. Subramani, J. Cell Biol. 127:1259–1273, 1994; A. P. Spong and S. Subramani, J. Cell Biol. 123:535–548, 1993). We demonstrate that PpPex1p and PpPex6p interact in an ATP-dependent manner. Genetically, the interaction was observed in a suppressor screen with a strain harboring a temperature-sensitive allele of PpPEX1 and in the yeast two-hybrid system. Biochemially, these proteins were coimmunoprecipitated with antibodies raised against either of the proteins, but only in the presence of ATP. The protein complex formed under these conditions was 320 to 400 kDa in size, consistent with the formation of a heterodimeric PpPex1p-PpPex6p complex. Subcellular fractionation revealed PpPex1p and PpPex6p to be predominantly associated with membranous subcellular structures distinct from peroxisomes. Based on their behavior in subcellular fractionation experiments including flotation gradients and on the fact that these structures are also present in a PpΔpex3strain in which no morphologically detectable peroxisomal remnants have been observed, we propose that these structures are small vesicles. The identification of vesicle-associated peroxins is novel and implies a role for these vesicles in peroxisome biogenesis. We discuss the possible role of the ATP-dependent interaction between PpPex1p and PpPex6p in regulating peroxisome biogenesis events.

scholarly journals α3β1 Integrin Is Required for Normal Development of the Epidermal Basement Membrane

1997 ◽  
Vol 137 (3) ◽  
pp. 729-742 ◽  
Author(s):  
C. Michael DiPersio ◽  
Kairbaan M. Hodivala-Dilke ◽  
Rudolf Jaenisch ◽  
Jordan A. Kreidberg ◽  
Richard O. Hynes
Keyword(s):  
Basement Membrane ◽  
Cultured Cells ◽  
Membrane Integrity ◽  
Matrix Proteins ◽  
Wild Type ◽  
Primary Keratinocytes ◽  
Laminin 5 ◽  
Skin Development ◽  
Neonatal Skin ◽  
Deficient Mice

Integrins α3β1 and α6β4 are abundant receptors on keratinocytes for laminin-5, a major component of the basement membrane between the epidermis and the dermis in skin. These integrins are recruited to distinct adhesion structures within keratinocytes; α6β4 is present in hemidesmosomes, while α3β1 is recruited into focal contacts in cultured cells. To determine whether differences in localization reflect distinct functions of these integrins in the epidermis, we studied skin development in α3β1-deficient mice. Examination of extracellular matrix by immunofluorescence microscopy and electron microscopy revealed regions of disorganized basement membrane in α3β1-deficient skin. Disorganized matrix was first detected by day 15.5 of embryonic development and became progressively more extensive as development proceeded. In neonatal skin, matrix disorganization was frequently accompanied by blistering at the dermal-epidermal junction. Laminin-5 and other matrix proteins remained associated with both the dermal and epidermal sides of blisters, suggesting rupture of the basement membrane itself, rather than detachment of the epidermis from the basement membrane as occurs in some blistering disorders such as epidermolysis bullosa. Consistent with this notion, primary keratinocytes from α3β1-deficient skin adhered to laminin-5 through α6 integrins. However, α3β1-deficient keratinocytes spread poorly compared with wild-type cells on laminin-5, demonstrating a postattachment requirement for α3β1 and indicating distinct roles for α3β1 and α6β4. Our findings support a novel role for α3β1 in establishment and/or maintenance of basement membrane integrity, while α6β4 is required for stable adhesion of the epidermis to the basement membrane through hemidesmosomes.

scholarly journals Pex17p Is Required for Import of Both Peroxisome Membrane and Lumenal Proteins and Interacts with Pex19p and the Peroxisome Targeting Signal–Receptor Docking Complex inPichia pastoris

1999 ◽  
Vol 10 (12) ◽  
pp. 4005-4019 ◽  
Author(s):  
William B. Snyder ◽  
Antonius Koller ◽  
Aaron Jobu Choy ◽  
Monique A. Johnson ◽  
James M. Cregg ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Critical Role ◽  
Coiled Coil ◽  
Matrix Proteins ◽  
Peroxisomal Membrane ◽  
Acid Protein ◽  
Targeting Signal ◽  
Carboxyl Terminal ◽  
Peroxisome Membrane ◽  
Amino Acid Protein

Pichia pastoris PEX17 was cloned by complementation of a peroxisome-deficient strain obtained from a novel screen for mutants disrupted in the localization of a peroxisomal membrane protein (PMP) reporter. PEX17 encodes a 267-amino-acid protein with low identity (18%) to the previously characterizedSaccharomyces cerevisiae Pex17p. Like ScPex17p, PpPex17p contains a putative transmembrane domain near the amino terminus and two carboxyl-terminal coiled-coil regions. PpPex17p behaves as an integral PMP with a cytosolic carboxyl-terminal domain.pex17Δ mutants accumulate peroxisomal matrix proteins and certain integral PMPs in the cytosol, suggesting a critical role for Pex17p in their localization. Peroxisome remnants were observed in the pex17Δ mutant by morphological and biochemical means, suggesting that Pex17p is not absolutely required for remnant formation. Yeast two-hybrid analysis demonstrated that the carboxyl terminus of Pex19p was required for interaction with Pex17p lacking the carboxyl-terminal coiled-coil domains. Biochemical evidence confirmed the interaction between Pex19p and Pex17p. Additionally, Pex17p cross-linked to components of the peroxisome targeting signal–receptor docking complex, which unexpectedly contained Pex3p. Our evidence suggests the existence of distinct subcomplexes that contain separable pools of Pex3p, Pex19p, Pex17p, Pex14p, and the peroxisome targeting signal receptors. These distinct pools may serve different purposes for the import of matrix proteins or PMPs.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

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