Many integral membrane proteins synthesized in the endoplasmic reticulum ultimately arrive at the cell surface to contact the cell environment. During transit through the Golgi and trans-Golgi network, proteins acquire post-translational modifications that can be used to track the appearance of such modified proteins at the cell surface. Cellular proteins can be treated with enzymes--e.g., sialidase or protease--or antibodies, or biotinylated to identify molecules that have reached the cell surface. Some proteins first enter the endocytic pathway before appearing at the cell surface; this is detected by treating the cells at 4 degrees and 37 degrees C. Analysis of the number of sialic acids on proteins of cells treated at 4 degrees C identifies proteins resident at the cell surface, while cells treated at 37 degrees C internalize the sialidase, which can then act with proteins in the endocytic compartments.
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http://dx.doi.org/10.1002/0471143030.cb1503s03 | DOI Listing |
Discov Nano
January 2025
Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, 710072, Shaanxi, China.
Human lens epithelial cells (hLECs) are critical for lens transparency, and their aberrant metabolic activity and gene expression can lead to cataract. Intracellular delivery to hLECs, especially to sub-cellular organelles (e.g.
View Article and Find Full Text PDFCell Mol Neurobiol
January 2025
Laboratory of Neurobiology, Centro de Investigaciones Medico Sanitarias (CIMES), University of Malaga, Calle Marqués de Beccaria, 3, Campus Teatinos s/n, 29010, Malaga, Spain.
Tetrameric AMPA-type ionotropic glutamate receptors are primary transducers of fast excitatory synaptic transmission in the central nervous system, and their properties and abundance at the synaptic surface are crucial determinants of synaptic efficacy in neuronal communication across the brain. The induction of long-term potentiation (LTP) leads to the insertion of GluA1-containing AMPA receptors at the synaptic surface, whereas during long-term depression (LTD), these receptors are internalized into the cytoplasm of the spine. Disruptions in the trafficking of AMPA receptors to and from the synaptic surface attenuate both forms of synaptic plasticity.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Human Biology Research Unit, Institute of Integrated Research, Institute of Science Tokyo, Bunkyo-ku, Tokyo 113-8510, Japan.
Intercellular transmission of messenger RNA (mRNA) is being explored in mammalian species using immortal cell lines. Here, we uncover an intercellular mRNA transfer phenomenon that allows for the adaptation and reprogramming of human primed pluripotent stem cells (hPSCs). This process is induced by the direct cell contact-mediated coculture with mouse embryonic stem cells under the condition impermissible for primed hPSC culture.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114.
Ependymoma (EPN) is a common form of brain tumor in children, often resistant to available cytotoxic therapies. Molecular profiling studies have led to a better understanding of EPN subtypes and revealed a critical role of oncogenes ZFTA-RELA fusion and EPHB2 in supratentorial ependymoma (ST-EPN). However, the immune system's role in tumor progression and response to therapy remains poorly understood.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
HHMI, The University of Texas at Austin, Austin, TX 78712.
Dynamic control of signaling events requires swift regulation of receptors at an active state. By focusing on the Arabidopsis ERECTA (ER) receptor kinase, which perceives peptide ligands to control multiple developmental processes, we report a mechanism preventing inappropriate receptor activity. The ER C-terminal tail (ER_CT) functions as an autoinhibitory domain: Its removal confers higher kinase activity and hyperactivity during inflorescence and stomatal development.
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