scholarly journals Structural and functional studies of erythrocyte membrane-skeleton by single-cell and single-molecule techniques

2019 ◽  
Vol 12 (01) ◽  
pp. 1830004
Author(s):  
Fulin Xing ◽  
Fen Hu ◽  
Jianyu Yang ◽  
Leiting Pan ◽  
Jingjun Xu
Keyword(s):  
Mechanical Properties ◽  
Single Cell ◽  
Erythrocyte Membrane ◽  
Single Molecule ◽  
Membrane Skeleton ◽  
Structure And Function ◽  
The Body ◽  
Extrusion Force ◽  
Functional Studies ◽  
And Function

As the indispensable oxygen-transporting cells, erythrocytes exhibit extreme deformability and amazing stability as they are subject to huge reversible shear stress and extrusion force during massive circulation in the body. The unique architecture of spectrin-actin-based membrane-skeleton is considered to be responsible for such excellent mechanical properties of erythrocytes. Although erythrocytes have been recognized for more than 300 years, myriad questions about membrane-skeleton constantly attract people’s attention. Here, we summarize the kinds of distinctive single-cell and single-molecule techniques that were used to investigate the structure and function of erythrocyte membrane-skeleton at macro and micro levels.

scholarly journals Evidence of Regeneration of Testicular and Epididymal Tissue Structure and Function Following Withdrawal from Sub-chronic Khat Exposure: Studies in the Rabbit Animal Model

2020 ◽  
pp. 10-23
Author(s):  
Albert W. Nyongesaa ◽  
Esther M. Malukib ◽  
Jemimah A. Simbaunib
Keyword(s):  
Body Weight ◽  
Chronic Exposure ◽  
Structure And Function ◽  
The Body ◽  
Endocrine Function ◽  
Eastern Africa ◽  
Blood Samples ◽  
Middle East Countries ◽  
Group I ◽  
And Function

Khat, Catha edulis, use is rampant in Eastern Africa and Middle East countries with associated reports of reproductive function impairment in the body of the user. Reports on recovery post long-term khat exposure are obscure. The present study investigated evidence of restoration of testicular and epididymal structure and function during withdrawal from cytotoxic damage caused by sub-chronic exposure of khat extract. Twenty-eight male rabbits were divided into 7 groups of 4 rabbits each. Group I (control) was administered normal saline while groups II, III and IV were administered 1.0 g/kg, 10 g/kg and 20 g/kg body weight of khat extract, respectively, via oral gavage on alternate days of the week for 12 weeks. Blood samples from animals were collected for hormonal assays followed by euthanasia using 26.4 mg/kg body weight of Sagatal sodium intramuscularly for testicular and epididymal histology. Group V, VI and VII were administered 1.0 g/kg, 10 g/kg and 20 g/kg body weight of khat extract, respectively, orally on alternate days of the week for 12 weeks followed by 1-month withdrawal period, blood samples collected for hormone assays and animals sacrificed for testicular and epididymal histology. High khat dose, 20 g/kg body weight, at sub-chronic exposure caused degeneration in spermatogenic cells with accompanying decrease in plasma FSH and testosterone. Histological output of Sertoli cells, Leydig cells and epididymal epithelium appeared unaffected in treatment groups. Post withdrawal data showed apparent regeneration of seminiferous epithelium and restoration of plasma FSH and testosterone comparable to control. It appears khat extract preferentially affected germ cell spermatogonia and subsequent daughter cells while stem cell spermatogonia were unaffected and contributed to regeneration of germinal epithelium and endocrine function.

Structural and functional studies of SAV1707 from Staphylococcus aureus elucidate its distinct metal-dependent activity and a crucial residue for catalysis

2021 ◽  
Vol 77 (5) ◽  
pp. 587-598
Author(s):  
Dong-Gyun Kim ◽  
Kyu-Yeon Lee ◽  
Sang Jae Lee ◽  
Seung-Ho Cheon ◽  
Yuri Choi ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Metal Binding ◽  
Binding Mode ◽  
Structure And Function ◽  
Functional Study ◽  
Functional Studies ◽  
Dependent Endonuclease ◽  
Metal Selectivity ◽  
Metal Binding Domain ◽  
And Function

The metallo-β-lactamase fold is the most abundant metal-binding domain found in two major kingdoms: bacteria and archaea. Despite the rapid growth in genomic information, most of these enzymes, which may play critical roles in cellular metabolism, remain uncharacterized in terms of structure and function. In this study, X-ray crystal structures of SAV1707, a hypothetical metalloenzyme from Staphylococcus aureus, and its complex with cAMP are reported at high resolutions of 2.05 and 1.55 Å, respectively, with a detailed atomic description. Through a functional study, it was verified that SAV1707 has Ni2+-dependent phosphodiesterase activity and Mn2+-dependent endonuclease activity, revealing a different metal selectivity depending on the reaction. In addition, the crystal structure of cAMP-bound SAV1707 shows a unique snapshot of cAMP that reveals the binding mode of the intermediate, and a key residue Phe511 that forms π–π interactions with cAMP was verified as contributing to substrate recognition by functional studies of its mutant. Overall, these findings characterized the relationship between the structure and function of SAV1707 and may provide further understanding of metalloenzymes possessing the metallo-β-lactamase fold.

Cellular structure and function

2021 ◽  
pp. 1-104
Keyword(s):  
Plasma Membrane ◽  
Nucleic Acids ◽  
Cellular Structure ◽  
Structure And Function ◽  
The Body ◽  
Signalling Pathways ◽  
Cellular Functions ◽  
Pharmacological Agents ◽  
Intracellular Organelles ◽  
And Function

‘Cellular structure and function’ covers the roles, structures, and functions of the main four types of macromolecules of the human body, namely proteins, lipids, carbohydrates, and nucleic acids. For these macromolecules, the roles and types of each class are discussed (for proteins this includes their roles as structural proteins and enzymes and their kinetics; for lipids, the roles and types of lipid found in the body are considered; for carbohydrates, their roles including structural and metabolic are discussed; and the structure of nucleic acids is described). Then follows a description of the organization of the cell, including the plasma membrane and its components, and the intracellular organelles. Cell growth, division, and apoptosis are covered, as are the formation of gametes, and finally the principles of how cellular functions can be modulated by pharmacological agents through receptors and signalling pathways are discussed.

scholarly journals Structure and Function of the Body

1969 ◽  
Vol 69 (5) ◽  
pp. 1075
Author(s):  
Faustena Blaisdell ◽  
Catherine Parker Anthony
Keyword(s):  
Structure And Function ◽  
The Body ◽  
And Function

scholarly journals Structural Characterization of Carbonic Anhydrase VIII and Effects of Missense Single Nucleotide Variations to Protein Structure and Function

2020 ◽  
Vol 21 (8) ◽  
pp. 2764
Author(s):  
Taremekedzwa Allan Sanyanga ◽  
Özlem Tastan Bishop
Keyword(s):  
Carbonic Anhydrase ◽  
Binding Site ◽  
Cross Correlation ◽  
Structure And Function ◽  
The Body ◽  
Conformational Sampling ◽  
Nucleotide Polymorphisms ◽  
Ip3 Receptor ◽  
Single Nucleotide ◽  
And Function

Human carbonic anhydrase 8 (CA-VIII) is an acatalytic isoform of the α -CA family. Though the protein cannot hydrate CO2, CA-VIII is essential for calcium (Ca2+) homeostasis within the body, and achieves this by allosterically inhibiting the binding of inositol 1,4,5-triphosphate (IP3) to the IP3 receptor type 1 (ITPR1) protein. However, the mechanism of interaction of CA-VIII to ITPR1 is not well understood. In addition, functional defects to CA-VIII due to non-synonymous single nucleotide polymorphisms (nsSNVs) result in Ca2+ dysregulation and the development of the phenotypes such as cerebellar ataxia, mental retardation and disequilibrium syndrome 3 (CAMRQ3). The pathogenesis of CAMRQ3 is also not well understood. The structure and function of CA-VIII was characterised, and pathogenesis of CAMRQ3 investigated. Structural and functional characterisation of CA-VIII was conducted through SiteMap and CPORT to identify potential binding site residues. The effects of four pathogenic nsSNVs, S100A, S100P, G162R and R237Q, and two benign S100L and E109D variants on CA-VIII structure and function was then investigated using molecular dynamics (MD) simulations, dynamic cross correlation (DCC) and dynamic residue network (DRN) analysis. SiteMap and CPORT analyses identified 38 unique CA-VIII residues that could potentially bind to ITPR1. MD analysis revealed less conformational sampling within the variant proteins and highlighted potential increases to variant protein rigidity. Dynamic cross correlation (DCC) showed that wild-type (WT) protein residue motion is predominately anti-correlated, with variant proteins showing no correlation to greater residue correlation. DRN revealed variant-associated increases to the accessibility of the N-terminal binding site residues, which could have implications for associations with ITPR1, and further highlighted differences to the mechanism of benign and pathogenic variants. SNV presence is associated with a reduction to the usage of Trp37 in all variants, which has implications for CA-VIII stability. The differences to variant mechanisms can be further investigated to understand pathogenesis of CAMRQ3, enhancing precision medicine-related studies into CA-VIII.

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