File:FcR triggering phagocytosis..jpg
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Image of FcγR triggering in phagocytosis
a) Engagement of oligomeric ligands with receptors in the absence of obvious receptor clustering leads to activation of TRPV2 in a PI(3)K-dependent manner, which results in membrane depolarization. How signals downstream of PI(3)K activate TRPV2 remains unclear. Phosphorylation of TRPV2, oligomerization of TRPV2 or recruitment of TRPV2 from intracellular compartment may trigger TRPV2 activation. (b) PtdIns(4,5)P2 (PI(4,5)P2) is synthesized by a combination of type II PI(4)K activated by membrane polarization and PIP(5)Kγ activated by Syk. PtdIns(4,5)P2 recruits actin-binding proteins for local actin depolymerization to change local plasma membrane fluidity, thus allowing FcγRs to move. (c) Higher order FcγR clustering strengthens the FcγR-mediated signaling, resulting in the activation of PIP(5)Kα and the generation of more PtdIns(4,5)P2, which is sufficient for actin polymerization with the aid of Wiskott-Aldrich syndrome protein (WASp) and Arp2/3. Actin polymerization induces pseudopodia and phagosomal cup formation. PtdIns(4,5)P2, FcγR and TRPV2 are concentrated in the phagosomal cup. PI, phosphoinositide; PI(4)P, phosphatidylinositol-4-phosphate; PI(3,4,5)P3, phosphatidylinositol-3,4,5-trisphosphate; PKC, protein kinase C; ER, endoplasmic reticulum.
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|current||20:21, 29 May 2014||900 × 779 (109 KB)||Z3399239||==FcγR_triggering_phagocytosis..jpg== Image of FcγR triggering in phagocytosis a) Engagement of oligomeric ligands with receptors in the absence of obvious receptor clustering leads to activation of TRPV2 in a PI(3)K-dependent manner, which results ...|