The mitochondrial import protein Mim1 promotes biogenesis of multispanning outer membrane proteins

Abstract The mitochondrial outer membrane contains translocase complexes for the import of precursor proteins. The translocase of the outer membrane complex functions as a general preprotein entry gate, whereas the sorting and assembly machinery complex mediates membrane insertion of β-barrel proteins of the outer membrane. Several α-helical outer membrane proteins are known to carry multiple transmembrane segments; however, only limited … Continue reading

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Nuclear envelope starts with a clean sheet

After mitosis, nuclear membranes form directly from ER cisternae before nuclear pore complex reassembly. At the start of mitosis, the nuclear envelope breaks down and merges with the endoplasmic reticulum (ER). At the same time, the nuclear pore complexes that mediate transport across the inner and outer membranes of the envelope also disassemble. Transmembrane pore proteins move into the ER, … Continue reading

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Multispan mitochondrial outer membrane protein Ugo1 follows a unique Mim1-dependent import pathway

Papić et al. 194 (3): 397 Abstract The mitochondrial outer membrane (MOM) harbors several multispan proteins that execute various functions. Despite their importance, the mechanisms by which these proteins are recognized and inserted into the outer membrane remain largely unclear. In this paper, we address this issue using yeast mitochondria and the multispan protein Ugo1. Using a specific insertion assay … Continue reading

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Formation of the postmitotic nuclear envelope from extended ER cisternae precedes nuclear pore assembly

Abstract During mitosis, the nuclear envelope merges with the endoplasmic reticulum (ER), and nuclear pore complexes are disassembled. In a current model for reassembly after mitosis, the nuclear envelope forms by a reshaping of ER tubules. For the assembly of pores, two major models have been proposed. In the insertion model, nuclear pore complexes are embedded in the nuclear envelope … Continue reading

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Tracing the origins of centrioles, cilia, and flagella

Abstract Centrioles/basal bodies (CBBs) are microtubule-based cylindrical organelles that nucleate the formation of centrosomes, cilia, and flagella. CBBs, cilia, and flagella are ancestral structures; they are present in all major eukaryotic groups. Despite the conservation of their core structure, there is variability in their architecture, function, and biogenesis. Recent genomic and functional studies have provided insight into the evolution of … Continue reading

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Nuclear translocation of AMPK-α1 potentiates striatal neurodegeneration in Huntington’s disease

Abstract Adenosine monophosphate–activated protein kinase (AMPK) is a major energy sensor that maintains cellular energy homeostasis. Huntington’s disease (HD) is a neurodegenerative disorder caused by the expansion of CAG repeats in the huntingtin (Htt) gene. In this paper, we report that activation of the α1 isoform of AMPK (AMPK-α1) occurred in striatal neurons of humans and mice with HD. Overactivation … Continue reading

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Nuclear translocation of AMPK-α1 potentiates striatal neurodegeneration in Huntington’s disease

Abstract Adenosine monophosphate–activated protein kinase (AMPK) is a major energy sensor that maintains cellular energy homeostasis. Huntington’s disease (HD) is a neurodegenerative disorder caused by the expansion of CAG repeats in the huntingtin (Htt) gene. In this paper, we report that activation of the α1 isoform of AMPK (AMPK-α1) occurred in striatal neurons of humans and mice with HD. Overactivation … Continue reading

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Transient binding of an activator BH3 domain to the Bak BH3-binding groove initiates Bak oligomerization

Abstract The mechanism by which the proapoptotic Bcl-2 family members Bax and Bak release cytochrome c from mitochondria is incompletely understood. In this paper, we show that activator BH3-only proteins bind tightly but transiently to the Bak hydrophobic BH3-binding groove to induce Bak oligomerization, liposome permeabilization, mitochondrial cytochrome c release, and cell death. Analysis by surface plasmon resonance indicated that … Continue reading

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α-Synuclein and ALPS motifs are membrane curvature sensors whose contrasting chemistry mediates selective vesicle binding

Pranke et al. 194 (1): 89 Abstract Membrane curvature sensors have diverse structures and chemistries, suggesting that they might have the intrinsic capacity to discriminate between different types of vesicles in cells. In this paper, we compare the in vitro and in vivo membrane-binding properties of two curvature sensors that form very different amphipathic helices: the amphipathic lipid-packing sensor (ALPS) … Continue reading

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POM121 and Sun1 play a role in early steps of interphase NPC assembly

Talamas and Hetzer 194 (1): 27 Abstract Nuclear pore complexes (NPCs) assemble at the end of mitosis during nuclear envelope (NE) reformation and into an intact NE as cells progress through interphase. Although recent studies have shown that NPC formation occurs by two different molecular mechanisms at two distinct cell cycle stages, little is known about the molecular players that … Continue reading

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