Signalling molecules fatty acid derivatives

In terms of their chemical structures, signalling molecules fall into five main categories (i) peptides, (ii) steroids, (iii) amino acids and their derivatives, (iv) fatty acid derivatives, and (v) nucleotides. 

Arachidonate, a 20 4 fatty acid derived from linoleate, is the major precursor of several classes of signal molecules prostaglandins, prostacyclins, thromboxanes, and leukotrienes (Figure 22.30). 

While almost all insect pheromones are fatty-acid-derived hydrocarbons (Baker, Chap. 27), crustacean pheromones are more diverse. They belong to various substance classes such as peptides (Rittschof and Cohen 2004), nucleotides (Hardege and Terschak, Chap. 19) or other small polar molecules (Kamio and Derby, Chap. 20), small nonpolar molecules (Ingvarsdottir et al. 2002), and possibly to ceramids (Asai et al. 2000). The higher diversity of waterborne pheromones again reflects the physical differences between the two media, with solubility in water being much less restrictive for the evolution of signal molecules than volatility in air. 

Plants also derive important signaling molecules from fatty acids. As in animals, a key step in the initiation of signaling involves activation of a specific phospholipase. In plants, the fatty acid substrate that is re-... 

Arachidonate, an essential precursor of prostaglandins and other signal molecules, is derived from linoleate. This 20 4 polyunsaturated fatty acid is the precursor of several classes of signal molecules— prostaglandins, prostacyclins, thromboxanes, and leukotrienes— that act as messengers and local hormones because of their transience. They are called eicosanoids because they contain 20 carbon atoms. Aspirin (acetylsalicylate), an anti-inflammatory and antithrombotic drug, irreversibly blocks the synthesis of these eicosanoids. 

Eicosanoids Oxygenated lipid signaling molecules containing 20 carbons derived from polyunsaturated fatty acids released from membrane phospholipids by the action of phospholipase A. These include the prostanoids produced by the cyclooxygenase pathway and the leukotrienes produced by the lipoxygenase pathway. 

Prostaglandin An oxygenated lipid signaling molecule that has a five-member ring system that is derived from arachidonic acid and other 20-carbon polyunsaturated fatty acids. The prostaglandins are hormone-like molecules that regulate cellular events near the area in which they are synthesized. 

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