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外文期刊>The biochemical journal
>Calcium-binding protein S100A7 and epidermal-type fatty acid-binding protein are associated in the cytosol of human keratinocytes
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Calcium-binding protein S100A7 and epidermal-type fatty acid-binding protein are associated in the cytosol of human keratinocytes
pExpression of epidermal-type fatty acid-binding protein (E-FABP) and S100A7 has previously been shown to be elevated in psoriatic skin, a disease characterized by abnormal keratinocyte differentiation. However, no causal relationship between the up-regulation of these proteins and the disease has been shown. E-FABP is thought to be involved in cytosolic fatty acid (FA) transport, whereas the role of S100A7 is still unknown. In this report, we show by overlay assays that E-FABP, immobilized on nitrocellulose, is able to capture S100A7 from cytosolic psoriatic protein extracts and vice versa, suggesting the formation of a complex between the two proteins. Using purified E-FABP and S100A7, the complex can be reconstituted only in presence of EDTA. Moreover, we show that increased EDTA concentrations in psoriatic cytosolic protein extracts enhance complex formation. Partial complex disruption was obtained by the addition of physiological concentrations of Znsup2+/sup (0.1 mM), whereas Casup2+/sup at 5 mM and Mgsup2+/sup at 30 mM had no effect. On the other hand, high Casup2+/sup concentrations (30 mM) resulted in partial complex disruption. Oleic acid-binding properties were observed for free E-FABP and the complex E-FABP–S100A7, but not for free S100A7. By using confocal microscopy we show that S100A7 and E-FABP are co-localized in the cytoplasm of differentiating keratinocytes from lesional psoriatic skin. These data indicate that formation of the E-FABP–S100A7 complex and its FA-binding function might be regulated at least by bivalent cations./p
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