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PDBsum entry 4z8g
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Protein binding
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PDB id
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4z8g
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References listed in PDB file
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Key reference
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Title
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How leiomodin and tropomodulin use a common fold for different actin assembly functions.
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Authors
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M.Boczkowska,
G.Rebowski,
E.Kremneva,
P.Lappalainen,
R.Dominguez.
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Ref.
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Nat Commun, 2015,
6,
8314.
[DOI no: ]
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PubMed id
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Abstract
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How proteins sharing a common fold have evolved different functions is a
fundamental question in biology. Tropomodulins (Tmods) are prototypical actin
filament pointed-end-capping proteins, whereas their homologues, Leiomodins
(Lmods), are powerful filament nucleators. We show that Tmods and Lmods do not
compete biochemically, and display similar but distinct localization in
sarcomeres. Changes along the polypeptide chains of Tmods and Lmods exquisitely
adapt their functions for capping versus nucleation. Tmods have alternating
tropomyosin (TM)- and actin-binding sites (TMBS1, ABS1, TMBS2 and ABS2). Lmods
additionally contain a C-terminal extension featuring an actin-binding WH2
domain. Unexpectedly, the different activities of Tmods and Lmods do not arise
from the Lmod-specific extension. Instead, nucleation by Lmods depends on two
major adaptations-the loss of pointed-end-capping elements present in Tmods and
the specialization of the highly conserved ABS2 for recruitment of two or more
actin subunits. The WH2 domain plays only an auxiliary role in nucleation.
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