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The Scientific Basis of Medicine
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Chris O'Callaghan, Rachel Allen
The fluid nature of the outer phospholipid membrane that surrounds the cell allows proteins to move around its surface. The cytosol is the site of many cellular reactions and contains all the necessary machinery for protein synthesis. A cytoskeleton of microfilaments, intermediate filaments and microtubules provides physical support for the various organelles and forms transport routes between them.
Introduction: Background Material
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
All living cells have a surrounding envelope referred to as the cell membrane, or plasma membrane. Animal cells are eukaryotic, that is, they have a well-developed nucleus and other membrane-bounded organelles, which are cell elements that perform some specialized functions. Figure 1.1 illustrates a typical eukaryotic cell and some of its organelles. The part of the cell that is outside the nucleus and bounded by the cell membrane is the cytoplasm. The cytosol, or intracellular fluid, is the liquid part of the cytoplasm, exclusive of organelles. It consists of a complex mixture of substances that are dissolved or suspended in water. The cell membrane is discussed in considerable detail in Sections 2.1 and 2.2. The following cell organelles are particularly relevant for our purposes.
The cell and tissues
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
These small organelles are found attached to the endoplasmic reticulum or floating freely in the cytosol. They are composed of ribosomal ribonucleic acid and proteins and are manufactured in the nucleolus of the nucleus and then transported into the cytosol. Their function is to act as centres for the production of proteins, which include enzymes. The proteins produced are used for metabolism, repair and replication within cells and for transport into the extracellular matrix.
Transglutaminase 2 mediates lung inflammation and remodeling by transforming growth factor beta 1 via alveolar macrophage modulation
Published in Experimental Lung Research, 2021
Young Chan Kim, Jeonghyeon Kim, Subin Kim, Boram Bae, Ruth Lee Kim, Eui-Man Jeong, Sang-Heon Cho, Hye-Ryun Kang
Transglutaminase is a calcium-dependent enzyme that catalyzes protein cross-linking, polyamination, or deamidation at selective glutamine residues.11 Among the several types of TGs with a high degree of sequence similarity,12 TG2 is the enzyme most widely expressed in numerous cell types. It is localized to multiple cell compartments, including the cytosol, mitochondria, and cell surface.13 Since TGF-β1 is synthesized in an inactive form, activation of latent TGF-β1 is required to initiate TGF-β1 signaling.14 TG2 cross-links the N-terminal region of latent TGF-β binding protein 1 to ECM proteins,15 whereas TGF-β1 increases membrane-associated extracellular TG2 expression in idiopathic pulmonary fibrosis. In mice, TG2 deletion suppresses pulmonary fibrosis after bleomycin challenge, which normally induces the release of the active form of TGF-β1 by alveolar macrophages.16
Protein lysine acetylation and its role in different human pathologies: a proteomic approach
Published in Expert Review of Proteomics, 2021
Orlando Morales-Tarré, Ramiro Alonso-Bastida, Bolivar Arcos-Encarnación, Leonor Pérez-Martínez, Sergio Encarnación-Guevara
Functional differences among protein sets become more apparent when we compare only the proteins uniquely quantified in each study. Regarding the cellular location, only the cytoplasmic and nuclear fraction appear as enriched. Figure 6 shows this comparison. It is important to note that Elia 2015 [226] shows the maximum enrichment of nuclear localization, which corresponds to the challenge that cells were subjected, to induce DNA damage and activate repair machinery. It is also necessary to mention that the set of proteins common to all conditions presents a significant enrichment of cytosolic proteins. This indicates that the fact that they are present in all the studies correlates with the fact that the proteins present in the cytosol are easier to extract than those enclosed in the membrane systems of the cell. When analyzing these protein subsets at the functional level (Figure 7), the differences between the experiments become more evident. While the specific proteins of Elia are fundamentally related to the repair of damage to the genetic material (as expected), the subset detected by Schölz [199] is linked to metabolism. Interestingly, the proteins unique to Tatham´s strongly correspond to cholesterol metabolism, correlating with cardiovascular disease and the inflammatory environment characteristic of autoimmunity. On the other hand, the acetylated proteins detected only by Hansen are related to the transduction of proliferation and growth signals.
Regulatory systems that mediate the effects of temperature on the lifespan of Caenorhabditis elegans
Published in Journal of Neurogenetics, 2020
Byounghun Kim, Jongsun Lee, Younghun Kim, Seung-Jae V. Lee
Autophagy, a process that degrades damaged organelles and dysfunctional components in cytosol, regulates multiple biological and pathological processes, including development, metabolism and stress resistance, and cancer and neurodegenerative diseases (Parzych & Klionsky, 2014; Yang & Klionsky, 2020). Autophagy also plays an important role in longevity of diverse organisms (Hansen, Rubinsztein, & Walker, 2018; Wong, Kumar, Mills, & Lapierre, 2020). Mutations in genes that are crucial for autophagy decrease lifespan in model organisms ranging from nematodes to mammals (Hansen et al., 2018). Conversely, overexpression of several autophagy regulators increases lifespan in multiple species (Aparicio, Hansen, Walker, & Kumsta, 2020; Hansen et al., 2018). In C. elegans, autophagy is a common effector process acting downstream of various longevity regimens. Such regimens include dietary restriction, reduced IIS, decreased TOR signaling, and impaired mitochondrial respiration (Hansen et al., 2018).