Figure 5.

Examples of three classes of heat-induced changes in enzyme activities within sphingolipid metabolism. Heat stress causes the activities of: phosphoserine phosphatase to increase (a); diacylglycerol (DAG) ethanolamine phosphotransferase to decrease (b); and sphingoid-1-phosphate phosphatase to decrease initially and subsequently to increase substantially, presumably due to gene expression that begins to increase as soon as the temperature rises (c). Grey bands indicate ranges of responses, while red lines show average trends.