Signal peptide peptidase

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The Signal Peptide Peptidase (SPP) and its homologs (SPPL2a/b/c, SPPL3) are a class of transmembrane aspartate proteases with the conserved motives YD ... GxGD ...PALL. Their sequences are highly conserved in different vertebrate species. Their substrates are Type II transmembrane proteins [1]. Physiologically SPP processes signal peptides of HLA preproteins. A 9 AS cleavage fragment is then presented on HLA-E receptors and modulates the activity of natural killer cells [2]. SPP also plays a pathophysiolocigal role; it cleaves the core protein of Hepatitis C virus and thus influences the reproduction rate of HCV [3]. SPPL2a/b promotes the intramembrane cleavage of TNFα in activated dendritic cells and might play an immunomodulatory role [4], [5].

[edit] Further reading

• Paetzel M, Karla A, Strynadka NC, Dalbey RE. 2002. Signal peptidases. Chem Rev. 102: 4549-80. [6]

[edit] External links

• UMich Orientation of Proteins in Membranes families/superfamily-178 - Calculated spatial position of type 1 signal peptidase in membrane
• MeSH signal+peptide+peptidase