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KONDOH/MACMILLAN( T9 p# X6 {4 V7 c
8 {% u. { C/ n5 L& dA target of blood pressure–lowering drugs harbors the unexpected ability to release GPI-anchored proteins. Gen Kondoh (Kyoto University, Kyoto, Japan), Junji Takeda (Osaka University, Osaka, Japan), and colleagues reveal that this enzyme, ACE, is both a peptidase and GPIase in one multifunctional package.ACE's peptidase activity is well studied〞it cleaves and activates angiotensin, which up-regulates blood pressure through hormonal changes. But Kondoh did not expect to find ACE in his screen for proteins that release GPI-anchored proteins from the cell surface.1 h3 B! P8 v+ @" i. Y7 J: }5 b S
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GPI deficiencies cause severe problems in fertility and development. GPI also links the prion protein to membranes. But the activities that release these linkages were not well-known. Now, Kondoh shows that a region of ACE distinct from its peptidase domain has this ability. Soluble prion protein protects against scrapie, so ACE, especially a peptidase-inactive form, may be a useful disease treatment.
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) N; O2 D& K6 JAs ACE was found in a mouse testicular preparation, the group examined sperm lacking the ACE GPIase activity. The mutant sperm were infertile and unable to release several GPI-linked proteins from their surface.1 w9 b1 a" ^& h. [) e9 t, K, W
8 y6 f- E1 {& U" l* @Anchored proteins were partly protected from ACE cleavage if they were in lipid rafts. By keeping GPI-linked fertilization factors in rafts, their release could be delayed until the raft disruption that occurs during capacitation.: O9 B' E4 u* u- X7 _9 r! x
( R1 K- c0 F) jReference:
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" _. F# X6 h+ e+ {) {" O" \Kondoh, G., et al. 2005. Nat. Med. doi:10.1038/nm1179(Sperm–egg binding (left) is lost when AC) |
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发表于 2009-3-6 08:53
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