1. Tropomyosins Current Biology
Peter W. Gunning, Edna C. Hardeman 
Current Biology 
Volume 27, Issue 1, Pages R8-R13 (January 2017)
DOI: /j.cub
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2. Figure 1
Strategies employed for the diversification of the composition of cytoskeletal actin filaments throughout evolution.
Bacteria, and possibly protists and plants, use multiple actins to generate non-exchangeable homopolymers that are functionally distinct. In contrast, fungi and animals use tropomyosin isoforms to diversify the composition of their filaments. The existence of many different tropomyosin-containing actin filaments as well as naked actin filaments allows these different filaments to collaborate in close proximity to yield complex structures, such as stress fibres. It is not clear whether the same functional collaboration of different filaments exists in bacteria, protists and plants. Please note that the actin cytoskeleton in mammals uses two functionally distinct isoforms, beta and gamma, which have been ignored for simplicity.
Current Biology  , R8-R13DOI: ( /j.cub )
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3. Figure 2
Working model for the regulation of lamellipodial persistence by tropomyosin.
Cortactin promotes and stabilises the Arp2/3-nucleated protrusive actin filament network. In order to translate protrusion into more stable filaments associated with adhesion, coronin 1B, along with SSH1L, activates cofilin via dephosphorylation, resulting in the severing of branched actin networks. This creates new free pointed ends to which tropomyosin preferentially binds, protecting filaments from further severing and branching and providing a more stable substrate for the recruitment of focal contact proteins; this promotes the maturation of focal adhesions to drive lamellipodial-based cell motility. In the absence of Tpm1.8/9, there is no mechanism to stabilise the protrusion and the instability of the Arp2/3 network allows the membrane to retract. This explains why the front of the lamellipodium consists of adjacent Arp2/3-rich zones and Tpm1.8/9-rich zones.
Current Biology  , R8-R13DOI: ( /j.cub )
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4. Figure 3
Tropomyosin isoforms regulate the interaction of actin filaments with motors and actin-binding proteins in an isoform-dependent manner.
Actin and tropomyosin form co-polymers in which the tropomyosin isoform can determine the manner in which the filament will interact with actin-binding proteins like actin depolymerising factor (ADF), cofilin and fascin and with myosin motors such as myosin II isoforms.
Current Biology  , R8-R13DOI: ( /j.cub )
Copyright © 2017 Elsevier Ltd Terms and Conditions