Interactions with membrane components

Interactions with Membrane Components. In aqueous systems milk fat globule membrane lipids and the non-lipid membrane solids were found to accelerate the oxidation of milk fat at 50°C, but exhibited antioxidant effects at 95°C (Chen, Z. Y. Nawar, W. W., University of Massachusetts at Amherst, unpublished data). 

In conclusion, in the case of resistant E. coli cultures, the increase in antibacterial activity of the more lipophilic benzylpyrimidines is due not to a favorable influence on the transport through the cell membrane but to their interaction with membrane components leading to membrane destruction and cell death. 

Figure 2 depicts the current concept of the mode of action of FSH on granulosa or Sertoli cells. The protein domain of the FSH molecule binds to specific FSH receptors in plasma membrane, while the carbohydrate moieties of FSH are believed to interact with membrane components either within or adjacent to the receptor molecule. Isolation and characterization of the FSH receptors will contribute to elucidating the binding site and the role of the carbohydrate moieties in the transduction of the hormonal signal. The binding of FSH to the receptors is followed by the activation of adenyl cyclase resulting in the accumulation of cAMP. 

Exterkate, F. A. (1977). Pyrrolidone carboxylyl peptidase in Streptococcus cremoris Dependence on the interaction with membrane components. J. Bacteriol. 129,1281-1288. 

Dmg receptors are chemical entities which are typically, but not exclusively, small molecules that interact with cellular components, frequently at the plasma membrane level (1,2). There are many types of receptors heat, light, immune, hormone, ion channel, toxin, and vims are but a few that can excite a cell. The receptor concept can be appHed generally to signal recognition processes where a chemical or physical signal is recognized. This recognition is translated into response (Fig. 3) and the process can be seen as a flow of information. 

In addition to the membrane-inserted core domain of Kv channels, their cytoplasmic domains have important roles for Kv-channel function [5]. Many of these functions are related to subunits assembly, channel trafficking to and from the plasma membrane, and interactions with cytoskeletal components (Fig. la). A tetramerization (T) domain for subunit assembly has been well defined in Shaker-channels, where it is localized in the amino-terminus. Other Kv-channels (e.g., eag, HERG, KvLQTl) may have comparable domains within the cytoplasmic carboxy-terminus. ER retention and retrieval signals have been found... 

As stated earlier, the primary site of association of [ H]MDA with brain synaptosomes is with membrane components, not with the intrasynaptic space. While the phenolic ends of these compounds may enable them to interact with hydrophobic environments of brain membrane components, their polar side chains may inhibit the ability of these compounds to move freely across the membranes, thus inhibiting internalization. The pKa of... 

It is likely that the predominantly positively charged amino acids of TAT and other CPPs will interact with anionic components on the surface of the cell membrane (85). This idea is supported by the observation that cell association with CPP liposomes in glycosaminoglycan-deficient Chinese hamster ovary (CHO) cells is greatly reduced and is competitively inhibited by the presence of heparin (88,93). Furthermore, the removal of the heparan sulfate chains by the action of glycosaminoglycan lyase also suppressed the transduction of the TAT protein (94). 

Membranes separate cells from their external environment, and the internal components of cells from each other. Many biochemical processes taking place within cells occur on a framework of membranes. Toxicant interactions with membranes figure prominently in many types of toxic effect. 

The receptors start a second messenger cascade that is initiated by activation of G-proteins in the cell. These, in turn, interact with membrane-bound adenylyl cyclase, which catalyzes the formation of cyclic adenine monophosphate (cAMP) and opening of cAMP-gated cation channels. Depolarization then brings about an action potential, which travels along the axon of the olfactory sensory neuron. Many of the molecular components of this cascade are olfactoiy specific. 

Deshayes S, Morris MC, Divita G, Heitz F. Interactions of amphipathic peptides with membrane components and consequences on the ability to dehver therapeutics. J Peptide Sci 2006 12 758-765. 

Among the earliest proposals to explain the mechanism of action of anesthetics is the concept that they interact physically rather than chemically with lipophilic membrane components to cause neuronal failure. However, this concept proposes that all anesthetics interact in a common way (the unitary theory of anesthesia), and it is being challenged by more recent work demonstrating that specific anesthetics exhibit selective and distinct interactions with neuronal processes and that those interactions are not easily explained by a common physical association with membrane components. Proposals for the production of anesthesia are described next. 

When metal interaction with subcellular components (membranes, chloroplasts, mitochondria) and enzymes is discussed, it is a prerequisite to take into account the... 

The lack of a hydrophobic term for the isolated enzyme system in Eq. (5.15) and the presence of such a term in Eq. 5.16 for the cell culture was presumed to be due to the interaction with Hpophihc components of the cell membrane. 

The concept that plasma membrane transport plays a key role in the regulation of intracellular thyroid hormone levels is supported by studies with a monoclonal antibody against an antigen exposed on rat liver cells [107], This antibody inhibited the uptake of different iodothyronines by rat hepatocytes under initial rate conditions as well as the metabolism of these compounds during prolonged incubations [107]. Uptake and metabolism of T4, T3 and rT3 were affected to the same extent, suggesting that a single system operates in the transport of different iodothyronines, which is opposite to the view advanced above. However, it is not excluded that the antibody interacts with a component of the plasma membrane and thereby affects multiple transport systems. 

The presence of adequate supplies of boron has been shown to be essential for the proper development of frogs and fish, and considerable evidence indicates that boron plays a vital role in other animals and humans." Although precise biochemical mechanisms are yet to be revealed for animals, it appears likely that boron interacts through reversible ester formation in significant and necessary ways with membrane components and enzymes in animal cells. 

Physical effects caused by polyethylene glycol bases include softening and liquefaction in mixtures with phenol, tannic acid, and salicylic acid. Discoloration of sulfonamides and dithranol can also occur and sorbitol may be precipitated from mixtures. Plastics, such as polyethylene, phenolformaldehyde, polyvinyl chloride, and cellulose-ester membranes (in filters) may be softened or dissolved by polyethylene glycols. Migration of polyethylene glycol can occur from tablet film coatings, leading to interaction with core components. 

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