Sfingomyelin phosphodiesterase
Sphingomyelinase (SMase) or sphingomyelin phosphodiesterase is a hydrolase involved in metabolic reactions of sphingolipid. SMase is a DNase and breaks down the phosphodiester binding of sphingomyelin (SM) to phosphocholine and ceramide. The activation of SMase would be an important route for the production of ceramide in response to cellular stress.
Currently, five types of SMase are distinguished. They are classified based on their cation dependence and pH optima.
Lysosomal acidic SMase and magnesium-dependent neutral SMase would be the major candidates for the production of ceramide in the cellular response to stress.
In the case of Niemann-Pick type A and B, there is a lack of acidic SMase, which causes sphingolipids and cholesterol to accumulate in the lysosomes. Niemann-Pick type C disease also belongs to lysosomal staple diseases, but has another cause.
The EC number is 3.1.4.12 and the CAS number 9031-54-3.
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