Direct interactions between talin and actin

Muguruma, Michio; Matsumura, Sueo; Fukazawa, Toshiyuki

doi:10.1016/0006-291x(90)90815-5

Cited by 128 publications

(65 citation statements)

References 19 publications

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“…These observations are consistent with experiments in i o showing that integrins are key determinants of the subcellular localization of talin [21,22]. Talin is also an F-actinbinding protein [13,23,24] and is reported to possess activity in both actin nucleation [25] and actin bundling [26]. Therefore talin has the potential to link integrins directly to the actin cytoskeleton.…”

Section: Introductionsupporting

confidence: 87%

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Talin contains three similar vinculin-binding sites predicted to form an amphipathic helix

et al. 1999

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Using recombinant talin polypeptides and an SDS\PAGE-blot overlay assay, we have previously identified three regions of talin that are involved in binding to vinculin [Gilmore, Wood, Ohanian, Jackson, Patel, Rees, Hynes and Critchley (1993) J. Cell Biol. 122, 337-347]. We have confirmed these observations by using a yeast two-hybrid assay and shown that talin residues 498-656, 852-950 and 1929-2029 are each capable of binding to vinculin residues 1-258. We have further defined the three vinculin-binding sites in talin to residues 607-636, 852-876 and 1944-1969 ; alignment of these sequences shows 59 % similarity, although there are only two identical residues. Predictions of secondary structure indicate that this vinculin-binding motif forms an amphipathic α-helix. The hydrophobic face of helix 607-636 contains three aligned leucines (residues 608, 615 and 622), which show conservative substitutions in the other two

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Section: Introductionsupporting

confidence: 87%

“…(A) The domain structure of talin, showing the positions of the binding sites for pp125 focal adhesion kinase, layilin [3], vinculin [27][28][29] and F-actin [13,23,24]. (B) The possible relationship between the three vinculin-binding sites and the C-terminal actin-binding site in a talin homodimer.…”

Section: Figure 7 Domain Structure Of Talinmentioning

confidence: 99%

Talin contains three similar vinculin-binding sites predicted to form an amphipathic helix

et al. 1999

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“…Our results clearly show that vinculin and talin occur in type I particle aggregates, where they could mediate the association of actin with the cytoplasmic tail of integrin (14,35,42,46,60). The proximity of actin filaments to /~-integrin is suggested by our observation that antibodies to the cytoplasmic tail of/~-integrin did not label that protein when overlying actin filaments are present.…”

Section: Aggregates Of Membrane Particlesmentioning

confidence: 49%

Structures linking microfilament bundles to the membrane at focal contacts

Samuelsson

Luther

Pumplin

et al. 1993

The Journal of Cell Biology

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Abstract. We used quick-freeze, deep-etch, rotary replication and immunogold cytochemistry to identify a new structure at focal contacts. In Xenopus fibroblasts, elongated aggregates of particles project from the membrane to contact bundles of actin microfilaments. Before terminating, a single bundle of microfilaments interacts with several aggregates that appear intermittently over a distance of several microns. Aggregates are enriched in proteins believed to mediate actin-membrane interactions at focal contacts, including B~-integrin, vinculin, and talin, but they appear to contain less t~-actinin and filamin. We also identified a second, smaller class of aggregates of membrane particles that contained/~-integrin but not vinculin or talin and that were not associated with actin microfilaments. Our results indicate that vinculin, talin, and ~-integrin are assembled into distinctive structures that mediate multiple lateral interactions between microfilaments and the membrane at focal contacts.F OCAL contacts are specialized structures where actin filaments converge and terminate at the plasma membrane (16,32,44,63,65). Interactions between the membrane and microfilaments involve several proteins that are concentrated at focal contacts, including integrin (e.g., references 17, 21, 22; reviewed in 1, 61) and cytoskeletal proteins such as vinculin (26), talin (13), fimbrin (9), tensin (71), paxillin (68), zyxin (5), and ot-actinin (40). Biochemical studies have suggested several ways in which these proteins could anchor microfilaments to the cytoplasmic surface of the plasma membrane at focal contacts. Early studies suggested that particular isoforms of integrin ("CSAT'; 47) bound talin, and that this complex then bound vinculin (35; reviewed in 15). Later studies showed that integrins could also bind tx-actinin (53). Thus, integrin could anchor actin filaments indirectly through the actin-binding protein, tx-actinin, as well as through talin and vinculin. If both of these mechanisms are important for actin-membrane interactions, one would expect all these proteins to be concentrated at focal contacts.Structural studies also suggest two models for microfilament-membrane interactions at focal contacts. Focal contacts are several microns long, and individual actin filaments course over this entire distance before terminating (8). These filaments could bind to the membrane laterally as they approach their termini. In this case, vinculin, talin, integrin, and other proteins of focal contacts would be expected to concentrate at many points along the filament length. Alter- natively, filaments could attach only at their termini. In this case, the proteins of focal contacts would be expected to occur only at the ends of microfilaments.Predictions of the relationship between actin microfilaments and the membrane, and of the distribution of proteins at focal contacts, can be tested by ultrastructural methods coupled with immunocytochemistry. We exposed the cytoplasmic surfaces of ventral membrane by mechanical shearing, the...

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“…No evidence has yet been obtained for any direct interaction between actin filaments and ezrin. Tàlin was believed not to directly interact with actin filaments, but recently the direct interaction between talin and actin was reported (Muguruma et al ., 1990) . The interaction of these band 4 .1-like proteins with actin filaments should be examined under various conditions, for example, in the presence of phospholipids and/or other protein factors .…”

Section: Discussionmentioning

confidence: 99%