Talin contains three actin-binding sites each of which is adjacent to a vinculin-binding site

Abstract

We have determined the sequence of chicken talin (2,541 amino acids, M(r) 271,881) which is very similar (89% identity) to that of the mouse protein. Alignments with the Caenorhabditis elegans and Dictyostelium discoideum talin sequences show that the N- and C-terminal regions of the protein are conserved whereas the central part of the molecule is more divergent. By expressing overlapping talin polypeptides as fusion proteins, we have identified at least three regions of the protein which can bind F-actin: residues 102–497, 951–1,327 and 2,269-2,541. The N-terminal binding site contains a region with homology to the ERM family of actin-binding proteins, and the C-terminal site is homologous to the yeast actin-binding protein Sla2p. Each of the actin-binding sites is close to, but distinct from a binding site for vinculin, a protein which also binds actin. The Pro1176 to Thr substitution found in talin from Wistar-Furth rats does not destroy the capacity of this region of the protein to bind actin or vinculin. Microinjection studies showed that a fusion protein containing the N-terminal actin-binding site localised weakly to stress fibres, whereas one containing the C-terminal site initially localised predominantly to focal adhesions. The former was readily solubilised, and the latter was resistant to Triton extraction. The N-terminal talin polypeptide eventually disrupted actin stress fibres whereas the C-terminal polypeptide was without effect. However, a larger C-terminal fusion protein also containing a vinculin-binding site did disrupt stress fibres and focal adhesions. The results suggest that, although both the N- and C-terminal regions of talin bind actin, the properties of these two regions of the protein are distinct.

Talin rod domain–containing protein 1 (TLNRD1) is a novel actin-bundling protein which promotes filopodia formation

“…Another major role of talin R7R8 is to bind actin (Hemmings et al, 1996), and TLNRD1 has previously been shown to bind actin (Gingras et al, 2010). Using a high-speed cosedimentation assay, we confirmed that TLNRD1-FL interacts with actin filaments (Fig.…”

“…Talin R7R8 is emerging as a major signaling hub, linking diverse cytoskeletal elements together (Goult et al, 2018). It forms part of a major actin-binding site (actin-binding site 2 [ABS2]) that spans R4-R8 (Atherton et al, 2015;Kumar et al, 2016;Hemmings et al, 1996). Talin R7R8 also binds to multiple other ligands, many of which contain leucine-aspartate motifs (LD motifs; Alam et al, 2014).…”

Universal Kinetics of the Onset of Cell Spreading on Substrates of Different Stiffness

“…In particular, in the nascent adhesions formed at the onset of spreading, kindlin was directly binding paxillin; paxillin was then recruiting FAK to these nascent adhesions. On the other hand, the important role of vinculin in several processes in the integrin-talin-FAK adhesion complex appears to be relevant mostly at the mature focal adhesion stage (Hemmings, Rees, Ohanian, Bolton, Gilmore, Patel, Priddle, Trevithick, Hynes, and Critchley, 1996, Margadant et al, 2011, Yao, Goult, Chen, Cong, Sheetz, and Yan, 2014, and we believe its role is to bind different adhesion complexes into a dense focal adhesion raft.…”

Talin in mechanotransduction and mechanomemory at a glance

“…LD-containing proteins that bind talin in this way include RIAM (Goult et al, 2013b), KANK family proteins (Bouchet et al, 2016), CDK1 (Gough et al, 2021), DLC1, paxillin (Zacharchenko et al, 2016) and tensin (Atherton et al, 2021 preprint). LD-independent folded rod binders include F-actin (Hemmings et al, 1996), synemin (Sun et al, 2008), moesin (Beaty et al, 2014) and the talin F3 domain that mediates autoinhibition (Goksoy et al, 2008;Goult et al, 2009). Unfolded (1) rod binders Currently only vinculin has been identified as binding to talin in its unfolded state.…”

“…additional cytoskeletal linkages (Ciobanasu et al, 2018;Hemmings et al, 1996), but its function is not well understood. Of these, vinculin is best characterized and can bind to the 11 vinculin binding sites (VBSs) distributed throughout the talin rod (Gingras et al, 2005).…”