Question

How are steroid hormones, phosphatidylinositol and eicosanoids similar and different in the locality of their effects? In their location in cell? In their structure?

Answer 1

steroid hormones and the eicosanoids are the lipid hormones which have lipid content in majority but their origination biomolecule differs such as the steroid hormones are derived from the carbohydrates whereas the eicosanoids are derived from fatty acids in plasma membrane.

the steroid hormones enters the cell and affect transcription or translation process. the main component of these hormones is the cholesterol whereas the eicosanoids from produced from arachidonic acid which is produced by the phospholipase clevage to steroid hormones. the main role of eicosanoids is in platelets functioning. the prostacyclin prevents the platelet clotting, produced by the endothelium cells, whereas thromboxane A2 causes platelet clotting and produced by the platelets .

these both hormones binds to a extracellular receptor when synthesised to perform its function . the hormones induce their actions at cellular and molecular levels where they bind to a secondary messenger G-protein receptors (GPCR) which activates the enzyme phospodiesterase which makes the phosphatidylinositol 4,5 biphosphate (PIP2) into a mediator i.e secondary messenger such as IP3 and DG . the IP3 diffuse into cytoplasm and releases calcium ions from ER while DG remains in membrane and activates protein kinase c for physiological changes.