Second messengers in signal transduction

In addition to its role as a bone component, calcium functions as a signaling substance. Ca "" ions act as second messengers in signal transduction pathways (see p. 386), they trigger exocytosis (see p. 228) and muscle contraction (see p. 334), and they are indispensable as cofactors in blood coagulation (see p. 290). Many enzymes also require Ca "" for their activity. The intracellular and extracellular concentrations of Ca "" are strictly regulated in order to make these functions possible (see B, C, and p.388). 

The properties of the prostanoid receptors, such as second messengers in signal transduction pathways, and localization in the eye are summarized in Table 2.1. Prostanoid receptors are widely distributed in the monkey and human eyes [5]. The expression and localization of the FP and EP receptor subtypes in the tissues was studied intensely by in-situ hybridization and immunohistochemistry to gain a better understanding of the ocular effects of the prostanoids and their analogues. This work suggests a wide distribution but differential expression of FP and EP receptor subtypes in human ocular tissues. The highest expression of FP receptor mRNA and protein was found in the corneal epithelium, ciliary... 

Their functions have been best studied in the model yeast Saccharomyces cerevisiae. Here, apart from structural functions, they play important roles as second messengers in signal transduction pathways, regulating diverse cellular processes like growth, nutrient uptake, heat stress response, cell wall synthesis... 

Forman, H. J., 2010. Reactive oxygen species and alpha, beta-unsaturated aldehydes as second messengers in signal transduction. 1203 35-44. 

Many lipid-derived products ai e now implicated as mediators or second messengers in signal transduction. The idea that membrane lipids are indeed hue signal reservoii s is presently more and more widely accepted. 

Dennis EA, Rhee SC, Billah MM, Hannun Y. Role of phospholipases in generating lipid second messengers in signal transduction. FASEB J 1991 5 2068-2077. 

Changes in second-messenger-associated signal transduction Changes in membrane-bound enzymes regulating neuronal activity Inhibition and aging of neuropathy enzymes Increases in glial fibrillary acidic protein in adults... 

GM-CSF and IL-3 have been shown to compete for receptors in some types of cells (e.g. eosinophils and KG-1 cells), indicating some structural homology between GM-CSF and IL-3 receptors, perhaps because they share certain subunits or adapter proteins. GM-CSF occupancy results in phosphorylation of certain proteins, and because the receptor possesses no inherent kinase activity, receptor occupancy must be linked to kinase activity via the generation of second messenger molecules. Pretreatment of cells with pertussis toxin abolishes the effects of GM-CSF, indicating the involvement of G-proteins in signal transduction. Priming of neutrophil functions with GM-CSF involves the activation of phospholipases A2 and D. 

Berridge, M. J., Irvine, R. F. (1984). Inositol trisphosphate, a novel second messenger in cellular signal transduction. Nature 312, 315-21. 

Calcium Is a Second Messenger in Many Signal Transductions... 

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