Tropomyosin is a tetramer under physiological salt conditions.
2010 (English)In: Cytoskeleton (Hoboken, N.J.), ISSN 1949-3592, Vol. 67, no 9, 599-607 p.Article in journal (Refereed) Published
Tropomyosin (TM) is a coiled-coil dimer of alpha-helical peptides, which self associates in a head- to-tail fashion along actin polymers, conferring stability to the microfilaments and serving a regulatory function in acto-myosin driven force generation. While the major amount of TM is associated with filaments also in non-muscle cells, it was recently reported that there are isoform-specific pools of TM multimers (not associated with F-actin), which appear to be utilized during actin polymerization and reformed during depolymerization. To determine the size of these multimers, skeletal muscle TM was studied under different salt conditions using gel-filtration and sucrose gradient sedimentation, and compared with purified non-muscle TM 1 and 5, as well as with TM present in non-muscle cell extracts and skeletal muscle TM added to such extracts. Under physiological salt conditions TM appears as a single homogenous peak with the Stokes radius 8.2 nm and the molecular weight (mw) 130,000. The corresponding values for TM 5 are 7.7 nm and 104,000, respectively. This equals four peptides, implying that native TM is a tetramer in physiological salt. It is therefore concluded that the TM multimers are tetramers.
Place, publisher, year, edition, pages
2010. Vol. 67, no 9, 599-607 p.
tropomyosin assembly;ionic strength dependence;microfilament organization;actin polymerization;cell motility
IdentifiersURN: urn:nbn:se:su:diva-44304DOI: 10.1002/cm.20470PubMedID: 20658558OAI: oai:DiVA.org:su-44304DiVA: diva2:360934