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Review
. 1999 Jul 26;146(2):267-72.
doi: 10.1083/jcb.146.2.267.

Signaling to actin dynamics

L M Machesky  1 , R H Insall
Affiliations
Review

Signaling to actin dynamics

L M Machesky et al. J Cell Biol. .
No abstract available

PubMed Disclaimer

Figures

Figure 1
Figure 1
Localization of actin, Arp2/3 complex, and Ena/VASP proteins. (A) Actin rockets on synthetic PIP2-containing lipid vesicles in Xenopus extracts. The lipid vesicle is shown in green and rhodamine-labeled actin is shown in red. (B) Costaining of filamentous actin (red) and VASP (green) on a cell infected with Listeria monocytogenes. VASP is clearly localized around the bacteria and at the tail–bacterium interface. (C) Costaining of filamentous actin (red) and the p41-Arc subunit of the Arp2/3 complex (green) in cells infected with Listeria monocytogenes. p41-Arc colocalizes along the length of the Listeria tails with filamentous actin. (D) Embryonic mouse hippocampal neuron in culture stained for filamentous actin (red) and Mena (green). The inset shows a close-up of a growth cone, with Mena at the tips of filopodia. (E) Swiss 3T3 fibroblasts costained for filamentous actin (red) and the p34-Arc subunit of the Arp2/3 complex (green). Photo credits: (A) Le Ma and Marc Kirschner; (B and C) Uwe Carl, Antonio Sechi, and Juergen Wehland; (D) Lorene Lanier and Frank Gertler.
Figure 2
Figure 2
Domain/motif organization of WASP and Ena/VASP proteins. WASP and N-WASP contain an EVH1 domain, which is a relative to the PTB and PH domain and is likely to interact specifically with polyproline containing ligands (Prehoda et al. 1999). All proteins in this extended family also contain various proline-rich sequences that can interact with profilin and with SH3 domain-containing proteins. Ena/VASP proteins contain a COOH-terminal EVH2 sequence. WASP and N-WASP contain a CRIB motif, which confers binding to the small GTPase Cdc42 and more weakly to Rac. All WASP-family members contain a WH2 motif which interacts with monomeric actin and a COOH-terminal A motif which binds to the p21-Arc subunit of the Arp2/3 complex.
Figure 3
Figure 3
Regulated treadmilling model for actin dynamics. (1) Various signals, such as receptor tyrosine kinase activation, PIP2 synthesis or serpentine receptor activation may trigger localization and/or activation of WASP/Scar proteins. WASP/Scar proteins in turn activate and localize the Arp2/3 complex to nucleate actin filaments near the plasma membrane. (2) Arp2/3 complex binds to the sides of actin filaments and rapidly nucleates branches. (3) The growing barbed ends of the filaments are dynamically regulated by capping protein and gelsolin under the control of membrane phospholipids. Ena/VASP proteins catalyze the elongation of newly nucleated filaments by shuttling activated (ATP-bound) actin monomers onto the growing (barbed) end. The shrinking (pointed) end of the filaments is depolymerizing with the help of cofilin to sever and dissociate monomers. (4) If the filaments depolymerize down to a branchpoint, Arp2/3 complex may fall off and be recycled to participate in nucleation. Blue triangles represent actin monomers, with the light blue T monomers being ATP-bound and the darker blue D monomers being ADP-bound. RTK represents receptor tyrosine kinase, PIP2 represents phosphatidylinositol 4,5 bisphosphate.
See this image and copyright information in PMC

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