Finding a Target
Nathan Keighley in Miraculous Medicines and the Chemistry of Drug Design, 2020
Most of the specific functions carried out by the plasma membrane are conducted by membrane proteins. As such, the type and quantities of these proteins in plasma membranes varies a great deal, depending on the function of that membrane. In myelin membranes, which function as the electrical insulators in nerve cells, less than 25% of the membrane mass is protein. By contrast, in the inner membranes of mitochondria, which are involved in energy transduction, are about 75% protein, by mass. Typically, cell membranes will have approximately 50% of their mass being proteins. Proteins molecules are much larger than the lipid molecules that comprise the bilayer, so there are many more lipid molecules in the membrane than there are proteins. The membrane proteins on the cell exterior will often have oligosaccharide (carbohydrate) molecules attached to them, which form a coat on the cell surface.
Airway Repair and Adaptation to Inhalation Injury
Jacob Loke in Pathophysiology and Treatment of Inhalation Injuries, 2020
The molecular mechanisms by which oxidizing gases cause cellular injury are not completely understood; however, the formation of free radicals by these agents is postulated to play a pivotal role. These mechanisms have been reviewed (Reck nagel and Glende, 1977; Pryor, 1982; Menzel, 1984). The gases, O3, NO2, and SO2 are strong oxidants that can react with many biochemical moieties to form free radicals. Free radicals formed by these interactions adversely affect the structure and function of cellular components such as proteins, especially enzymes containing sulfhydryl groups (SH), nucleic acids, and, more importantly, the cellular plasma membrane. The plasma membrane provides the containment of all cellular and organelle contents, and its permeability characteristics regulate the molecular species that enter and exit the cell and its organelles. The membrane is composed of lipoproteins rich in polyenoic long-chain fatty acids that are prone to undergo rancid or peroxidation decomposition under certain conditions. Free radicals, once formed, can react readily with molecular oxygen to form organic peroxy free radicals. When a peroxy free radical reacts with a phospholipid fatty acid side chain, it not only denatures the molecule but also produces another new organic free radical; this process is known as linear propagation of lipid hydroperoxide formation. Furthermore, new free radicals can be produced by the decomposition of organic peroxide via a number of cellular biochemical mechanisms (see Recknagel and Glende, 1977, for review).
From cells to systems
Nick Draper, Helen Marshall in Exercise Physiology, 2014
Cells typically have three components: the cell or plasma membrane, the nucleus and the remaining contents of the cell known as the cytoplasm (see Figure 3.2). The plasma membrane is a very thin structure that encloses every cell and keeps it separate from its surrounding environment. The nucleus, normally the largest single unit in the cell, contains the DNA, the genetic blueprint for controlling the operations of the cell, and the ribonucleic acid (RNA), a single stranded version of DNA which, amongst other things, controls protein synthesis within the cell. The cytoplasm comprises the inside of the cell except for the nucleus. It is made up of a gel-like substance, cytosol, which houses and protects nine main sorts of small structures called organelles. These organelles serve a variety of roles for the cell. An illustration of one such organelle, a mitochondrion, is provided in Figure 3.4. Mitochondria are the power plants of many cells and are responsible for producing about 90% of human energy.
Computational modeling of stretch induced calcium signaling at the apical membrane domain in umbrella cells
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Amritanshu Gupta, Rohit Manchanda
We define the cytoplasm under the apical plasma membrane as the sub-plasma membrane space (SPMS) and denote its volume as LSPMS. UCs in the rabbit bladder epithelium have a typical length of 60 − 120 μm and a height of ∼10 μm (Lewis and Hanrahan 1990). Given the tightly packed morphological architecture at the apical membrane domain in UC (Jost et al. 1989; Hudoklin et al. 2012), we estimate a depth of 2.5 μm underneath the apical surface area as the spatial extent of the SPMS. Given the morphological organisation under this segment of the apical membrane, we assume that a majority of the vesicle pool (0.9 LFV) and sub-apical mitochondria (0.5 Lmito) occupy the SPMS. Accounting for the high density of vesicles and mitochondria in the 2.5 μm depth under the apical membrane, we estimate that the cytoplasm in the SPMS accounts for around ∼ 1.5–2% of the UC volume.
The impact of busulfan on the testicular structure in prepubertal rats: A histological, ultrastructural and immunohistochemical study
Published in Ultrastructural Pathology, 2023
Reem Ibrahim Abd El-Hay, Walaa H.E. Hamed, Nesreen Mostafa Omar, Dalia Refat El-Bassouny, Salwa A. Gawish
The spermatogonia had large euchromatic nuclei with peripheral heterochromatin clumps and wide perinuclear space. Their cytoplasm showed dense mitochondria and free ribosomes. Wide intercellular spaces between spermatogenic cells were also observed (Figure 10c). Primary spermatocytes showed irregular nuclei. The cytoplasm was moderately electron dense and exhibited disrupted mitochondria and wide cisterns of rough endoplasmic reticulum (Figure 10d). Some round spermatids showed irregular outline and had euchromatic nuclei covered with acrosomal cap and their cytoplasm exhibited vesicular peripherally distributed mitochondria. Other round spermatids had shrunken nuclei and were covered with irregular acrosomal caps. The cytoplasm exhibited chromatoid body close to the nucleus, vacuoles and lysosomes (Figure 11a). The sperm tail included a middle piece, a principal piece and an end piece. Some middle, principal and end pieces appeared similar to those of the control group. Mitochondrial sheath contained vacuolated mitochondria in some middle pieces and was completely defective in others. Some transverse sections in the middle piece were surrounded by a single plasma membrane and exhibited excess cytoplasm with residual bodies. Other sections exhibited excess cytoplasm with many vacuoles and lipid droplets (Figure 11b,c).
Advances, challenge and prospects in cell-mediated nanodrug delivery for cancer therapy: a review
Published in Journal of Drug Targeting, 2023
Wuhao Wei, Yuansheng Zhang, Zhizhe Lin, Xin Wu, Wei Fan, Jianming Chen
The cell membrane is made up of thousands of different proteins, carbohydrates and lipids, which have the potential for chemical modification [91]. In addition, the chemical modification does not rely exclusively on naturally available cell surface molecules; the complexity of cell membranes provides options for introducing other functional groups for some conjugation reactions. Unlike pristine cells, modified cells enable convenient conjugations with therapeutics and particles via versatile chemistry tools. For example, thiols on the cell membrane can be used for drug coupling reactions with targeting units such as antibodies and polypeptides [92]. In addition [93], the ligand adhered to NPs through chemical coupling to improve the therapeutic effect by combining the ligand with the ligand on the cell surface.
Related Knowledge Centers
- Cytoplasm
- Extracellular Space
- Integral Membrane Protein
- Lipid Bilayer
- Membrane Fluidity
- Membrane Protein
- Phospholipid
- Cholesterol
- Biological Membrane
- Cell