Interaction with plasma membrane

Studies from our laboratories by Pantarotto et al. (2004a, b), Wu et al. (2005) and Kostarelos et al. (2007) using covalently functionalised CNTs (1,3-dipolar cycloaddition reaction chemistry) have reproducibly described that CNTs were uptaken by cells via pathways other than endocytosis. This work has experimentally observed that CNTs were able to interact with plasma membranes and cross into the cytoplasm without the apparent need of engulfment into a cellular compartment... 

Flavonoids can also interact with membrane proteins, such as those functioning as receptors, transporters, channels, and enzymes, and potentially affect their biological activities. A summary of recent advances on the study of flavonoid interactions with plasma membrane proteins is presented in Table 4.2. 

HS interact with nutrient assimilation of both macro- and micro-elements, by enhancing the nutrient use efficiency. This capacity is related to both (a) HS chelating properties and (b) an interaction with plasma membrane enzymatic constituents. 

Besides the genomic pathway, the nongenomic pathway of AR also has been reported in oocytes (57), skeletal muscle cells (58), osteoblasts (59,60), and prostate cancer cells (61,62). As compared to the genomic pathway, the nongenomic actions of steroid receptors are characterized by the rapidity of the action, which varies from seconds to an hour or so, and by interaction with plasma membrane-associated signaling pathways (63). Nevertheless, the structural basis for nongenomic action is direct interactions between AR and cytosolic proteins from different signaling pathways, which could be closely... 

Jones, D.L., Kochian, L.V., 1997. Aluminum interaction with plasma membrane hpids and enzyme metal binding sites and its potential role in A1 cytotoxicity. FEES Lett. 400, 51-57. 

Interactions with plasma membrane-associated proteins... 

If the plasma membrane is relatively impermeable, how do most molecules enter a cell How is selectivity of this movement established Answers to such questions are important in understanding how cells adjust to a constantly changing extracellular environment. Metazoan organisms also must have means of communicating between adjacent and distant cells, so that complex biologic processes can be coordinated. These signals must arrive at and be transmitted by the membrane, or they must be generated as a consequence of some interaction with the membrane. Some of the major mechanisms used to accomplish these different objectives are listed in Table 41-3. 

It has been proposed " that the mechanism(s) of action of gymnemic acids and ziziphins is a biphasic, model-membrane penetration-process. The model suggested that the modifier molecules interact first with the receptor-cell plasma-membrane surface. It was postulated that this initial interaction involves a selective effect on taste perception, including the transduction and quality specification of the sweet stimuli, and selective depression of sweetness perception. Following the initial interaction, the modifier molecules interact with the membrane-lipid interior to produce a general disruption of membrane function and a nonselective effect on taste... 

Khakh, B. S., Fisher, J. A., Nashmi, R., Bowser, D. N. and Lester, H. A. (2005). An angstrom scale interaction between plasma membrane ATP-gated P2X2 and alpha4beta2 nicotinic channels measured with fluorescence resonance energy transfer and total internal reflection fluorescence microscopy. J. Neurosci. 25, 6911-20. 

Investigations of the cellular effects of radiofrequency radiation provide evidence of damage to various types of avian and mammalian cells. These effects involve radiofrequency interactions with cell membranes, especially the plasma membrane. Effects include alterations in membrane cation transport, Na+/K+-ATPase activity, protein kinase activity, neutrophil precursor membrane receptors, firing rates and resting potentials of neurons, brain cell metabolism, DNA and RNA synthesis in glioma cells, and mitogenic effects on human lymphocytes (Cleary 1990). 

Also, the interaction of these nucleosides with cellular constituents of intact L1210 leukemia cells was studied.76 Rapid reaction with plasma membrane and soluble, intracellular thiols was demonstrated, as well as a good correlation between the extent of plasma membrane alkylation in vitro and the biological activity in vivo. 

The phagocyte partially digests the antigen and presents the processed antigen on its outer plasma membrane. T cells that interact with these membrane-bound processed antigens are stimulated to proliferate. 

As with normal hydrocarbon-based surfactants, polymeric micelles have a core-shell structure in aqueous systems (Jones and Leroux, 1999). The shell is responsible for micelle stabilization and interactions with plasma proteins and cell membranes. It usually consists of chains of hydrophilic nonbiodegradable, biocompatible polymers such as PEO. The biodistribution of the carrier is mainly dictated by the nature of the hydrophilic shell (Yokoyama, 1998). PEO forms a dense brush around the micelle core preventing interaction between the micelle and proteins, for example, opsonins, which promote rapid circulatory clearance by the mononuclear phagocyte system (MPS) (Papisov, 1995). Other polymers such as pdty(sopropylacrylamide) (PNIPA) (Cammas etal., 1997 Chung etal., 1999) and poly(alkylacrylicacid) (Chen etal., 1995 Kwon and Kataoka, 1995 Kohorietal., 1998) can impart additional temperature or pH-sensitivity to the micelles, and may eventually be used to confer bioadhesive properties (Inoue et al., 1998). 

Sun, IX. Crane, FX. (1990). Interactions of antitumor drugs with plasma membranes. In Oxidore-duction at the Plasma Membrane (Crane, F.L., Morre, D.J., Low, H., eds.), pp. 257-280, CRC Press, Boca Raton. 

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