Inositols conformational requirements

The NHR contains also the conserved Calcineurin docking site, PxlxIT, required for the physical interaction of NEAT and Calcineurin. Dephosphorylation of at least 13 serines residues in the NHR induces a conformational change that exposes the nuclear localization sequences (NLS), allowing the nuclear translocation of NEAT. Rephosphorylation of these residues unmasks the nuclear export sequences that direct transport back to the cytoplasm. Engagement of receptors such as the antigen receptors in T and B cells is coupled to phospholipase C activation and subsequent production of inositol triphosphate. Increased levels of inositol triphosphate lead to the initial release of intracellular stores of calcium. This early increase of calcium induces opening of the plasma membrane calcium-released-activated-calcium (CRAC) channels,... 

Barker and Shaw80 have recently shown that compounds which contain a cis-cis-1,2,3-triol system, in a six-membered ring, form relatively stable complexes with the periodate ion at a pH of about 7. Steric considerations suggest that the axial-equatorial-axial conformation is required. As expected, one mole of neo-inositol forms a complex with two moles of periodate, but rac-, muco-, and mi/o-inositols form no such complexes. Although mj/o-inositol has a cis-cis-1,2,3-triol system, the conformation XL required... 

Thomas W, Qian H, Chang C, Karnik S (2000) Agonist-induced phosphorylation of the angiotensin II (AT( 1 A)) receptor requires generation of a conformation that is distinct from the inositol phosphate-signaling state. J Biol Chem 275 2893-2900... 

Cyclitols do not form alkylidene derivatives with the same ease as acyclic carbohydrates. However, the technique of Dangschat and Fischer, wherein zinc chloride catalysis is used, enables the formation of isopropylidene derivatives. They made brilliant use of this reaction in their elucidation of the structures of shikimic acid, quinic acid, conduritol, and mj/o-inositol (see above). The structures of the naturally occurring methyl ethers, pinitol and quebrachitol, were determined with the aid of this reaction (7, ISa, b), L-Inositol and cpi-inositol can be converted to triisopropylidene derivatives (7). This requires acetonation of trans hydroxyl groups. A chair conformation of the ring does allow vicinal trans hydroxyl groups in the equatorial plane to approach one another closely (7). 

Although complete accord has not been reached, lindane appears to be a metabolic antagonist for microorganisms that require inositol 1S2). Lindane is a hexachlorocyclohexane insecticide that is thought to have the same conformation as myo-inositol. 

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