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Solute Translocations
Published in Lelio G. Colombetti, Biological Transport of Radiotracers, 2020
Determination of the molecular nature of the transport carrier represents one of the most intriguing and difficult problems available to the investigator of biological transport. That the carrier is — or is at least tightly associated with — a protein is most evident from considerations of solute specificity, the genetics of defective systems of transport,24-26 and studies of the effects of protein-specific chemical reagents on transport processes. The periplasmic, solute-binding proteins of gram-negative bacteria undoubtedly provide an important degree of structural specificity for solute uptake,27-29 but it is doubtful that they represent the carrier itself. During recent years, much attention has focused on the carrier in eukaryotic systems. A protein of the human erythrocyte membrane (Band 3) has been identified as the major anion carrier of that cell,30,31 and considerable progress has been made in the isolation of the glucose carrier from the membrane of the rat adipocyte.32,33 These important studies may soon result in a molecular description of mediated transport at the levels of both solute recognition and translocation per se.
Bioengineering Aids to Reproductive Medicine
Published in Sujoy K. Guba, Bioengineering in Reproductive Medicine, 2020
Interactions are at all levels of organization of the body. Cellular level interactions are particularly important. The cell membrane has been suggested as a likely site for the radiations to act. Many investigators have looked in to the transport across the erythrocyte membrane. Ion transfer rates are affected. Exposure to 2.45-GHz continuous wave microwave at 6 W/kg (approximate field strength 87 V/m) produces inhibition of sodium/potassium ATPase activity at 25 C. It is hypothesized that the structural elements of the enzyme undergo modification. In vitro studies have also shown effects on other cell functions. Cell type specific inhibitory effects on proliferation of cultured cells exposed to 2.45-GHz microwaves has been seen. The growth of synchronized L60T cells was altered by microwave exposure only during the mitotic (M) and intermitotic (Gl) phases of the cell cycle. Whether these actions have significance relating to the response of gametes of reproduction exposed to microwaves is not clear. But a more chronic irradiation of male germ cells of the mouse does in some cases produce chromosomal aberrations although results from different studies are quite variable.64,65 Comparable well controlled studies for the ovum are not reported.
Hemolytic Anemia Associated with Red Cell Membrane Defects
Published in Harold R. Schumacher, William A. Rock, Sanford A. Stass, Handbook of Hematologic Pathology, 2019
A schematic representation of the erythrocyte membrane skeleton is shown in Fig. 1. Spectrin heterodimers, composed of α and β chains, self-associate into filamentous tetramers that are the main constituent of the membrane skeleton. Approximately six spectrin tetramers are attached to each short actin filament to form a two-dimensional network. This network is attached to the inner face of the lipid bilayer via an adapter protein, ankyrin, and the integral membrane protein band 3 (the anion channel), the spectrin network interacts with a second integral membrane protein, glycophorin C, through protein 4.1, a molecule that also stabilizes the spectrin–actin association. Mutations affecting many of the protein constituents have been described that give rise to inherited hemolytic anemias.
Efficacy of cytochemical tests in gene analysis of hereditary spherocytosis: a case study of six patients with different disease subtypes
Published in Hematology, 2021
Atsushi Shibuya, Hiroaki Kawashima, Masato Tanaka
Hereditary spherocytosis (HS) is the most prevalent congenital disease that causes haemolytic anaemia due to abnormalities in the erythrocyte membrane. In Japan, patients with HS account for 60% of all cases of congenital haemolytic anaemia [1]. The erythrocyte membrane mainly consists of integral membrane proteins such as band 3 and a skeletal protein complex consisting of α- and β-spectrin, ankyrin, protein 4.1, protein 4.2, and actin. These membrane skeletal proteins interact with the integral membrane protein (band 3) to form an ankyrin – band 3 complex with spectrin tetramers, and form a junctional complex comprising actin, protein 4.2, protein 4.1, and band 3 (without ankyrin). Additionally, band 3 proteins exist in the membrane as a mixture of dimers and tetramers; dimers not linked to the ankyrin complex are known as free mobile band 3 [2.]
SLC2A3 rs12842 polymorphism and risk for Alzheimer’s disease
Published in Neurological Research, 2020
Stylianos Arseniou, Vasileios Siokas, Athina-Maria Aloizou, Polyxeni Stamati, Alexios-Fotios A. Mentis, Zisis Tsouris, Metaxia Dastamani, Eleni Peristeri, Varvara Valotassiou, Dimitrios P. Bogdanos, Georgios M. Hadjigeorgiou, Efthimios Dardiotis
The brain relies heavily on glucose, as its main energy source. Specific membrane transporters are required in order for hydrophilic substances, such as glucose, to cross the blood-brain barrier (BBB) [20]. Glucose transport is mediated by three families of solute carriers: (a) the Major Facilitator Superfamily (MFS) glucose SLC2 family of facilitated transporters, GLUTs, (b) the SLC5 family of active sodium-driven glucose transporters (SGLTs), and (c) the SLC50 family of uniporters (SWEETs) [21]. The most highly encountered glucose transporters (GLUTs) in the brain are GLUT1 and GLUT3. GLUT1 is the product of the SLC2A1 gene, and it is predominantly expressed in the human erythrocyte membrane, the endothelial cells of the BBB, and astrocytes [22]. GLUT3, on the other hand, is encoded by the SLC2A3 gene, which is specifically expressed in neurons [23], and it is consequently named the neuronal glucose transporter [24]. In the brain, GLUT1 mediates the transport of glucose from circulating blood in the microvasculature to the interstitial fluid [25]. Following the above process, GLUT3 transports glucose from the extracellular space into the neuron [26].
Association between the membrane transporter proteins and type 2 diabetes mellitus
Published in Expert Review of Clinical Pharmacology, 2020
Thus, an increased erythrocyte membrane microviscosity was already been studied by fluorescence depolarization spectroscopy in diabetic patients [94]. However, membrane fluidity has also been shown to be decreased in diabetic erythrocytes [94]. Lipid composition and lipid–protein interactions play the most crucial roles in maintaining the erythrocyte membrane fluidity. Kamada and Otsuji studied the properties of erythrocyte membrane in diabetic patients using electron spin resonance with stearic acid spin labels (SAL): 5-, 12-, and 16-SAL [94]. They observed significantly reduced erythrocyte membrane fluidity with 16-SAL as a probe in diabetic patients. However, there were no changes observed in fluidity values using 5- or 12-SAL. Therefore, it was concluded that the reduced fluidity was localized in deeper sites (hydrophobic region) of the erythrocyte membrane in diabetic patients [94].