Case 19 Purification of Rat Kidney Sphingosine Kinase

Background Sphingolipid metabolites have recently been shown to be involved in cell viability. For example, ceramide has been shown to stimulate apoptosis, or programmed cell death, whereas sphingosine-1phosphate (SPP) promotes cell survival. A number of different factors influence the levels of ceramide and SPP in the cell, as shown in Figure 19.1. Clearly, the balance of ceramide and SPP will be one of the many factors that influences whether a cell lives or dies. An understanding of the biochemical processes involved in regulating these sphingolipids has important applications in the treatment of cancer. We will concentrate on sphingosine1-phosphate (SPP). SPP is synthesized in the cell from sphingosine and ATP as shown in Figure 19.2. The enzyme that catalyzes the reaction is sphingosine kinase. In this case, we will study the purification of the sphingosine kinase enzyme.