Emergence and subsequent functional specialization of kindlins during evolution of cell adhesiveness.
Bottom Line: Kindlin appears to originate from a duplication of the sequence encoding the N-terminal fragment of talin (the talin head domain) with a subsequent insertion of the PH domain of separate origin.The presence of this segment enables K2 but not K3 to localize to focal adhesions.Thus emergence and subsequent functional specialization of kindlins allowed multicellular organisms to develop additional tissue-specific adaptations of cell adhesiveness.
Affiliation: Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.Show MeSH
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Mentions: The results of BLASTP searches demonstrated that kindlin is a chimeric protein consisting of the N-terminal part of talin and the fragment of a PH domain–containing protein (Figure 2). With the exception of the PH domain–containing sequence, kindlins are homologous to talins (Figure 2 and Supplemental Figure S2). Sequence similarity between human talin 1 and K2 is highly significant (e < 10−18; Supplemental Figure S2). Moreover, in BLASTP searches for kindlins, metazoan talins appear as the next-most-similar family. This similarity suggests that kindlins originated from an ancestor of metazoan talins. This result is in agreement with another recently published study proposing that the FERM domain originated from a proto-talin protein in a unicellular or proto-multicellular organism (Ali and Khan, 2014).
Affiliation: Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.