1,826 research outputs found

    Distinct stages in the recognition, sorting, and packaging of proTGFα into COPII-coated transport vesicles.

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    In addition to its role in forming vesicles from the endoplasmic reticulum (ER), the coat protein complex II (COPII) is also responsible for selecting specific cargo proteins to be packaged into COPII transport vesicles. Comparison of COPII vesicle formation in mammalian systems and in yeast suggested that the former uses more elaborate mechanisms for cargo recognition, presumably to cope with a significantly expanded repertoire of cargo that transits the secretory pathway. Using proTGFα, the transmembrane precursor of transforming growth factor α (TGFα), as a model cargo protein, we demonstrate in cell-free assays that at least one auxiliary cytosolic factor is specifically required for the efficient packaging of proTGFα into COPII vesicles. Using a knockout HeLa cell line generated by CRISPR/Cas9, we provide functional evidence showing that a transmembrane protein, Cornichon-1 (CNIH), acts as a cargo receptor of proTGFα. We show that both CNIH and the auxiliary cytosolic factor(s) are required for efficient recruitment of proTGFα to the COPII coat in vitro. Moreover, we provide evidence that the recruitment of cargo protein by the COPII coat precedes and may be distinct from subsequent cargo packaging into COPII vesicles

    Homogeneous and Isotropic Cosmology, the Schwarzschild Solution, and Applications

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    Classically, the physics of the universe is described by Newton\u27s Laws of Motion and Newton\u27s Law of Universal Gravitation. In most cases, the results predicted by Newton\u27s theories accurately agree with experimental observations. However, under certain limitations, classical theories may yield slight deviation from observations, such as when the speed of an object approaches the speed of light. At the extreme, classical theory completely fails to explain the motion of photons, which are massless particles of light. In 1915, Albert Einstein published the General Theory of Relativity. Einstein\u27s theory provides a new perspective to a better understanding of the physics describing this universe. In this paper, we attempt to introduce some of the prerequisite material in differential geometry and investigate the general theory of relativity, along with some of its solutions from a mathematical point of view. We study homogeneous and isotropic cosmology, and the Schwarzschild solution. Finally, we will discuss some of their applications and significance
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