Cell surface alterations, mechanism

The binding of a hormone to its receptor initiates intracellular events that direct the hormone s action. Ultimately, all hormones produce their effects by altering intracellular protein activity. However, the mechanism by which this occurs depends on the location of the hormone receptor. Receptors are typically located on the cell surface or in the cell nucleus. As a result, most hormones carry out their effects by means of two general mechanisms ... 

Should the barrier presented by the secondary plant surface be breached, defence mechanisms may operate in the bark (i.e., secondary cortex and phloem) of woody plants, limiting pathogen development. These include chemical defences and structural barriers resulting from cell wall alterations... 

The effects of a chemical in a tissue frequently depend on the chemical s interaction with cell surface or cytoplasmic receptors. In some cases, a chemical interacts directly with the cell membrane and alters its permeability. The pharmacodynamic actions of drugs are usually mediated by interactions with a receptor, and a drug often competes with endogenous ligands of a receptor. The toxicity of environmental chemicals can also depend on and be mediated by interactions with receptors. In some cases, the responses are different for chemical exposures at different fetal stages of development, and it is possible to explain the different responses by the chronology of the development of fetal receptor systems. The fetus may develop receptor systems for a compound before it develops the ability to metabolize that compound thus, a low level of an active chemical can have greater and more persistent effects in the fetus than in the mother, whose metabolism limits the duration and extent of the effect. This is one mechanism for selective developmental toxicity of chemicals. 

Mechanosensing is postulated to involve many different cellular and extracellular components. Mechanical forces cause direct stretching of protein-cell surface integrin binding sites that occur on all eukaryotic cells. Stress-induced conformational changes in the extracellular matrix may alter integrin structure and lead to activation of several secondary messenger pathways within the cell. Activation of these pathways leads to altered reg-... 

Transformation Cell changes manifested by escape from control mechanisms, generally resulting in increased growth potential, alterations in the cell surface, and karyotypic abnormalities. Cell transformation generally occurs as a result of the acquisition of genetic information as by a virus entering the cell. 

The proposed mechanism of action is by alteration of bacterial cell surfaces so that aggregation and attachment is reduced. 

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