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- Holmfeldt, Per, et al.
(författare)
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The Schistosoma mansoni protein SM16/SmSLP/SmSPO-1 is a membrane-binding protein that lacks the proposed microtubule-regulatory activity
- 2007
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Ingår i: Molecular and biochemical parasitology (Print). - : Elsevier BV. - 0166-6851 .- 1872-9428. ; 156:2, s. 225-234
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Tidskriftsartikel (refereegranskat)abstract
- Sm16/SmSLP/SPO-1 (Sm16) has been identified as a developmentally regulated protein that is released from specific glands of the Schistosoma mansoni parasite during skin penetration. Sm16 has been ascribed both anti-inflammatory activities and a functional similarity with the conserved cytosolic tubulin-binding protein stathmin/Op18. Here we used a cell line to confirm signal peptide-dependent secretion and to define the secreted form of Sm16 for production in E. coli. We present evidence from both in vitro experiments and studies on transfected human cells that refute any functional similarity with stathmin/Op18. Instead of an Op18-like activity, we found that targeting of Sm16 to the cytosol of human cells, which was achieved by ectopic expression of Sm16 lacking the signal peptide, results in a caspase-dependent apoptotic response. Interestingly, by analysis of recombinant preparations we found that the secreted form of Sm16 is a lipid bilayer-binding protein that efficiently binds to the surface of diverse cell types by a polyanion-independent mechanism, which results in uptake by endocytosis. While the significance of the pro-apoptotic activity exerted by cytosolic Sm16 remains unclear, the present findings on cell-surface-binding properties of Sm16 seems likely to be of functional relevance during skin penetration of the parasite.
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| 2. |
- Lundmark, Richard, et al.
(författare)
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Expression and properties of sorting nexin 9 in dynamin-mediated endocytosis
- 2005
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Ingår i: Methods in Enzymology. - : Elsevier. - 0076-6879 .- 1557-7988. ; 404, s. 545-556
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Tidskriftsartikel (refereegranskat)abstract
- Sorting nexin 9 (SNX9) is identified as an important regulator of dynamin function in clathrin-mediated endocytosis. SNX9 recruits dynamin to the plasma membrane and promotes its GTPase activity, resulting in membrane constriction and ultimate transport vesicle scission. This chapter describes procedures to express recombinant SNX9, to biochemically characterize the cytosolic complex between SNX9 and dynamin, and to identify additional interacting partners of SNX9. Assays are presented to investigate the requirements for SNX9-dependent membrane recruitment of dynamin in vitro and in vivo.
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| 3. |
- Lundmark, Richard, et al.
(författare)
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SNX9 - a prelude to vesicle release
- 2009
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Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 122:1, s. 5-11
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Tidskriftsartikel (refereegranskat)abstract
- The sorting nexin SNX9 has, in the past few years, been singled out as an important protein that participates in fundamental cellular activities. SNX9 binds strongly to dynamin and is partly responsible for the recruitment of this GTPase to sites of endocytosis. SNX9 also has a high capacity for modulation of the membrane and might therefore participate in the formation of the narrow neck of endocytic vesicles before scission occurs. Once assembled on the membrane, SNX9 stimulates the GTPase activity of dynamin to facilitate the scission reaction. It has also become clear that SNX9 has the ability to activate the actin regulator N-WASP in a membrane-dependent manner to coordinate actin polymerization with vesicle release. In this Commentary, we summarize several aspects of SNX9 structure and function in the context of membrane remodeling, discuss its interplay with various interaction partners and present a model of how SNX9 might work in endocytosis.
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