The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

Serine-palmitoyl transferase activity in cultured human keratinocytes.

Sphingolipids comprise approximately 25% of the stratum corneum lipids and are considered critical constituents of the epidermal permeability barrier. Whether sphingoid base structures are synthesized in the epidermis or whether they are derived from circulating or dermal sources is not known. We report here the initial characterization of serine-palmitoyl transferase (EC; SPT), the rate-limiting enzyme in the synthesis of sphingolipids, from cultured human neonatal keratinocytes. Subcellular fractionation studies demonstrated that 79% of the total cellular SPT activity was associated with the microsomes. The specific activity of keratinocyte SPT was 270 +/- 20 pmol/min per mg of microsomal protein, a level significantly higher than activities reported in other tissues. Keratinocyte SPT showed an apparent Km for L-serine of 0.40 (+/- 0.04 mM, with an alkaline pH optimum (8.2 +/- 0.4). Keratinocyte SPT utilizes palmitoyl-CoA preferentially over other saturated or unsaturated acyl-CoA substrates; increasing acyl-CoA chain lengths above C16 by one or two carbons was less detrimental to activity than similar decrements in chain length. Finally, the mechanism-based inhibitors L-cycloserine and beta-chloro-L-alanine, demonstrated potent inhibition of keratinocyte SPT activity, with 50% inhibitory concentrations of approximately 3.0 and 25 microM, respectively. In summary, we have found that cultured human neonatal keratinocytes contain unusually high levels of serine-palmitoyl transferase activity, and that the substrate specificity of keratinocyte SPT may determine the base composition of epidermal sphingolipids.[1]


  1. Serine-palmitoyl transferase activity in cultured human keratinocytes. Holleran, W.M., Williams, M.L., Gao, W.N., Elias, P.M. J. Lipid Res. (1990) [Pubmed]
WikiGenes - Universities