In plasma membranes, most of glycosylphosphatidylinositol (GPI)-anchored proteins would be associated with rafts, a category of ordered microdomains enriched in sphingolipids and cholesterol (Ch). They would be also concentrated in the detergent resistant membranes (DRMs), a plasma membrane fraction extracted at low temperature. Preferential localization of GPI-anchored proteins in these membrane domains is essentially governed by their high lipid order, as compared to their environment. Changes in the temperature are expected to modify the membrane lipid order, suggesting that they could affect the distribution of GPI-anchored proteins between membrane domains. Validity of this hypothesis was examined by investigating the temperature-dependent localization of the GPI-anchored bovine intestinal alkaline phophatase (BIAP) into model raft made of palmitoyloleoylphosphatidylcholine/sphingomyelin/cholesterol (POPC/SM/Chl) supported membranes. Atomic force microscopy (AFM) shows that the inserted BIAP is localized in the SM/Chl enriched ordered domains at low temperature. Above 30 degrees C, BIAP redistributes and is present in both the 'fluid' POPC enriched and the ordered SM/Chl domains. These data strongly suggest that in cells the composition of plasma membrane domains at low temperature differs from that at physiological temperature.
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http://dx.doi.org/10.1002/jmr.835 | DOI Listing |
mLife
December 2024
State Key Laboratory of Mycology, Institute of Microbiology Chinese Academy of Sciences Beijing China.
Glycosylphosphatidylinositol (GPI) anchoring is one of the conserved posttranslational modifications in eukaryotes that attach proteins to the plasma membrane. In fungi, in addition to plasma membrane GPI-anchored proteins (GPI-APs), some GPI-APs are specifically released from the cell membrane, secreted into the cell wall, and covalently linked to cell wall glucans as GPI-anchored cell wall proteins (GPI-CWPs). However, it remains unclear how fungal cells specifically release GPI-CWPs from their membranes.
View Article and Find Full Text PDFbioRxiv
December 2024
Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, 955 Main Street, Buffalo NY 14203.
Secretory cargos are exported from the ER via COPII coated vesicles that have an inner matrix of Sec23/Sec24 heterotetramers and an outer cage of Sec13/Sec31 heterotetramers. In addition to COPII, Sec13 is part of the nuclear pore complex (NPC) and the regulatory SEA/GATOR complex in eukaryotes, which typically have one Sec13 orthologue. The kinetoplastid parasite has two paralogues: TbSec13.
View Article and Find Full Text PDFDev Cell
December 2024
Department of Neurobiology, University of Utah, Salt Lake City, UT, USA. Electronic address:
The apical extracellular matrix (aECM), organized by polarized epithelial cells, exhibits complex structures. The tectorial membrane (TM), an aECM in the cochlea mediating auditory transduction, exhibits highly ordered domain-specific architecture. α-Tectorin (TECTA), a glycosylphosphatidylinositol (GPI)-anchored ECM protein, is essential for TM organization.
View Article and Find Full Text PDFJ Virol
November 2024
Virus and Immunity Unit, Institut Pasteur, Université Paris Cité, CNRS UMR3569, Paris, France.
Membrane fusion occurs at the early stages of SARS-CoV-2 replication, during entry of the virus, and later during the formation of multinucleated cells called syncytia. Fusion is mediated by the binding of the viral Spike protein to its receptor ACE2. Lipid rafts are dynamic nanodomains enriched in cholesterol and sphingolipids.
View Article and Find Full Text PDFGlycobiology
December 2024
Institute for Glyco-core Research (iGCORE), Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
It remains a mystery why nature evolved the unique structural characteristics of GPI-anchored proteins (GPI-APs) and continues to sustain the complex, energy-intensive process of synthesizing these proteins. GPI-APs, despite their small size, rely on the coordinated activity of nearly 30 genes for their synthesis and remodeling, raising important evolutionary questions. The biological advantages of GPI-APs lie in their ability to rapidly redistribute across the cell membrane, localize within lipid rafts, utilize unique intracellular trafficking pathways, and function as both membrane-bound and soluble proteins.
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