Weak acid response element

The elemental reactions are, however, rather complicated and remain the subject of debate. For many studies on the kinetics of silicon oxide etching, identifying the fluoride species in the solution responsible for the etching reactions has been a major concern. This is because HF is a weak acid, which ionizes only partially to fluoride ions, and its aqueous solutions may contain a significant quantity of fluorine in the form of un-ionized HF and partially ionized bifluoride HFJ. 

SV23 characterized by a four amino acid insertion in the LBD adds an extra loop between helices 6 and 7. This isoform interacts weakly with CAR response elements and with various coactivators [61-65]. This variant was capable of transactivating CYP2B6 and MDR1 reporters in some studies but not CYP3A4 and IJGT1A1 reporters [61-65], Recently, it has been shown that upon RXRa overexpression SV23 shows RXR-dependent transactivation activity and interaction with SRC-1 as well as RXR-dependent response to clotrimazole and androstanol [66]. 

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