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Mitochondrial β-barrel proteins are essential for the transport of metabolites, ions and proteins. The sorting and assembly machinery (SAM) mediates their folding and membrane insertion. We report the cryo-electron microscopy structure of the yeast SAM complex carrying an early eukaryotic β-barrel folding intermediate. The lateral gate of Sam50 is wide open and pairs with the last β-strand (β-signal) of the substrate-the 19-β-stranded Tom40 precursor-to form a hybrid barrel in the membrane plane. The Tom40 barrel grows and curves, guided by an extended bridge with Sam50. Tom40's first β-segment (β1) penetrates into the nascent barrel, interacting with its inner wall. The Tom40 amino-terminal segment then displaces β1 to promote its pairing with Tom40's last β-strand to complete barrel formation with the assistance of Sam37's dynamic α-protrusion. Our study thus reveals a multipoint guidance mechanism for mitochondrial β-barrel folding.
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http://dx.doi.org/10.1038/s41594-022-00897-2 | DOI Listing |
Nat Rev Mol Cell Biol
September 2025
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA.
The defining property of eukaryotic cells is the storage of heritable genetic material in a nuclear compartment. For eukaryotic cells to carry out the myriad biochemical processes necessary for their function, macromolecules must be efficiently exchanged between the nucleus and cytoplasm. The nuclear pore complex (NPC) - which is a massive assembly of ~35 different proteins present in multiple copies totalling ~1,000 protein subunits and architecturally conserved across eukaryotes - establishes a size-selective channel for regulated bidirectional transport of folded macromolecules and macromolecular assemblies across the nuclear envelope.
View Article and Find Full Text PDFEur Arch Otorhinolaryngol
September 2025
Department of Otolaryngology Head And Neck Surgery, Far Eastern Memorial Hospital, No. 21, Section 2, Nan-Ya South Road, New Taipei City, Taiwan.
Introduction: Anterior glottic webs are epithelium-covered fibrous tissue formations at the anterior commissure, leading to synechiae between the bilateral vocal folds. They manifest with symptoms ranging from hoarseness to airway obstruction. However, treating anterior glottic webs are challenging due to their high recurrence rates.
View Article and Find Full Text PDFMed Eng Phys
October 2025
University of Missouri, Department of Physical Therapy, Columbia, MO, USA. Electronic address:
Measurable neuromotor control deficits during functional task performance could provide objective criteria to aid in concussion diagnosis. However, many tools which measure these constructs are unidimensional and not clinically feasible. The purpose of this study was to assess the classification accuracy of a machine learning model using features measured by a clinically feasible movement-based assessment system (Mizzou Point-of-care Assessment System (MPASS) between athletes with and without concussion.
View Article and Find Full Text PDFInt J Biol Macromol
September 2025
Department of Computational Biology, Indraprastha Institute of Information Technology Delhi (IIIT-Delhi), Okhla Phase III, New Delhi, 110020, India; Infosys Centre for Artificial Intelligence, Indraprastha Institute of Information Technology Delhi (IIIT-Delhi), Okhla Phase III, New Delhi, 110020, In
Understanding the structural and functional diversity of toxin proteins is critical for elucidating macromolecular behavior, mechanistic variability, and structure-driven bioactivity. Traditional approaches have primarily focused on binary toxicity prediction, offering limited resolution into distinct modes of action of toxins. Here, we present MultiTox, an ensemble stacking framework for the classification of toxin proteins based on their molecular mode of action: neurotoxins, cytotoxins, hemotoxins, and enterotoxins.
View Article and Find Full Text PDFBiomed Pharmacother
September 2025
Department of Biomedical Sciences, Institute of Health, Jimma University, Jimma 378, Ethiopia; Division of Research & Development, Lovely Professional University, Phagwara 144411, India. Electronic address:
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by cognitive decline and the accumulation of misfolded proteins, including amyloid-beta and hyperphosphorylated tau, which impair neuronal function and promote cell death. These misfolded proteins disrupt proteostasis by forming toxic aggregates that exacerbate disease progression. Molecular chaperones, such as heat shock proteins, actively maintain protein homeostasis by assisting in proper folding, preventing aggregation, and promoting the clearance of misfolded proteins.
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