The ROle of Membranes in Cells and Organisms
Lukas K. Buehler in Cell Membranes, 2015
This chapter introduces the importance of cell membranes to the structure, function, and origin of cells. Constructed on a universal design—a lipid bilayer with membrane proteins embedded throughout and anchored to its surface—cell membranes form self-enclosed vesicular structures that separate cells from their surroundings, control exchange of molecules between the cell’s interior and its environment, promote adhesion and signaling with other cells, and contain a complex enzymatic machinery that supports the cell’s growth and shape. The role of membranes in transport, signaling, adhesion, and metabolism explains the large number of diseases associated with altered membrane protein function, which makes these proteins prominent drug targets.
Fundamental Concepts and an Introduction to the Cell
Thomas Millar in Biochemistry Explained, 2018
This chapter introduces to the idea that lipid and water solubility is a major foundation stone of biochemistry. Cell membranes, being composed mainly of lipids, provide a barrier to the chemicals, and therefore there must be special (bio)chemical mechanisms for the nutrients or signals to pass across the cell membrane. By contrast, the blood also needs to be able to transport lipids or lipid-soluble substances, and again there is a (bio)chemical process that enables this to happen. A cell is more than a lipid bag containing water, it is really an outer lipid bag or cell membrane containing several smaller lipid bags or compartments. In addition to the functions carried out by the subcellular compartments, cells have a particular shape. They can also change their shape and move when required. The shape of a cell and its ability to move comes from a group of structural chemicals called cytoskeletal proteins.
Physiology of excitable cells
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2015
This chapter examines the physiology of some excitable cells. It also examines the structure of the cell membrane and the ionic basis for the resting membrane potential. The chapter explores voltage-sensitive membrane ion channels are described and their role in the action potential. It Peripheral proteins on the inside and outside have different functions; glycoproteins have their sugar residues on the outside, and transporting enzymes bind adenosine triphosphate (ATP) on the inside. The cell membrane can be thought of as a layer of insulation covered on both sides by conducting material. This structure is traversed by protein channels that determine ionic permeability and the resultant electrical potential across the membrane. Potassium diffuses down this concentration gradient out of the cell, but this movement cannot continue indefinitely as it is opposed by electrical forces. Proteins are the main intracellular anions, but they also have little effect as they cannot traverse the membrane.
Evaluation of the Toxic Potency of Selected Cadmium Compounds on A549 and CHO-9 Cells
Published in International Journal of Occupational Safety and Ergonomics, 2014
Cytotoxicity of cadmium sulphide, oxide and chloride was tested using A549 and CHO-9 cells. Metabolic activity of cells (MTT test) and cell membrane permeability (NRU test) were used as cytotoxicity endpoints. The results revealed unexpectedly low toxicity of cadmium sulphide as compared to chloride and oxide. This preliminary report does not provide any explanation for this effect, but the result may nevertheless be interesting for future studies of toxicity mechanisms of cadmium compounds. First cadmium compounds caused damage or change in the permeability of cell membranes, then inhibition of metabolic activity of mitochondria. It cannot be ruled out that the cell lysosomes are at first exposed to the effect of cadmium.
Coating nanoparticles with cell membranes for targeted drug delivery
Published in Journal of Drug Targeting, 2015
Targeted delivery allows drug molecules to preferentially accumulate at the sites of action and thus holds great promise to improve therapeutic index. Among various drug-targeting approaches, nanoparticle-based delivery systems offer some unique strengths and have achieved exciting preclinical and clinical results. Herein, we aim to provide a review on the recent development of cell membrane-coated nanoparticle system, a new class of biomimetic nanoparticles that combine both the functionalities of cellular membranes and the engineering flexibility of synthetic nanomaterials for effective drug delivery and novel therapeutics. This review is particularly focused on novel designs of cell membrane-coated nanoparticles as well as their underlying principles that facilitate the purpose of drug targeting. Three specific areas are highlighted, including: (i) cell membrane coating to prolong nanoparticle circulation, (ii) cell membrane coating to achieve cell-specific targeting and (iii) cell membrane coating for immune system targeting. Overall, cell membrane-coated nanoparticles have emerged as a novel class of targeted nanotherapeutics with strong potentials to improve on drug delivery and therapeutic efficacy for treatment of various diseases.
Menin localization in cell membrane compartment
Published in Cancer Biology & Therapy, 2016
Xin He, Lei Wang, Jizhou Yan, Chaoxing Yuan, Eric S. Witze, Xianxin Hua
Menin is encoded by the MEN1 gene, which is mutated in an inherited human syndrome, multiple endocrine neoplasia type 1(MEN1). Menin is primarily nuclear protein, acting as a tumor suppressor in endocrine organs, but as an oncogenic factor in the mixed lineage leukemia, in a tissue-specific manner. Recently, the crystal structures of menin with different binding partners reveal menin as a key scaffold protein that functionally interacts with various partners to regulate gene transcription in the nucleus. However, outside the nucleus, menin also regulates multiple signaling pathways that traverse the cell surface membrane. The precise nature regarding to how menin associates with the membrane fraction is poorly understood. Here we show that a small fraction of menin associates with the cell membrane fraction likely via serine palmitoylation. Moreover, the majority of the membrane-associated menin may reside inside membrane vesicles, as menin is protected from trypsin-mediated proteolysis, but disruption of the membrane fraction using detergent abolishes the detection. Consistently, cellular staining for menin also reveals the distribution of menin in the cell membrane and the punctate-like cell organelles. Our findings suggest that part of intracellular menin associates with the cell membrane peripherally as well as resides within the membrane vesicles.
Related Knowledge Centers
- Mitochondria
- Cell Nucleus
- Endoplasmic Reticulum
- Plastids
- Vacuoles
- Gram
- Bacteriorhodopsins