Regulatory properties of tropomyosin effects of length, isoform, and N-terminal sequence

Maytum, Robin and Konrad, Manfred and Lehrer, Sherwin S. and Geeves, Michael A. (2001) Regulatory properties of tropomyosin effects of length, isoform, and N-terminal sequence. Biochemistry, 40 (24). pp. 7334-7341. ISSN 0006-2960 . (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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The regulatory properties of naturally occurring tropomyosins (Tms) of differing lengths have been examined. These Tms span from 4 to 7 actin subunits. Native proteins have been used to study the common 7 actin-spanning skeletal and smooth muscle variants and expressed recombinant proteins to study the shorter fibroblast 5a, 5b, yeast Tm1 and yeast Tm2 Tms (6, 6, 5, and 4 actin-spanning variants, respectively). The yTm2 has been overexpressed in Escherichia coli with N-terminal constructs equivalent to those previously used for yTm1 [Maytum, R., et al. (2000) Biochemistry 39, 11913]. The regulation of myosin subfragment 1 (S1) binding to actin by Tm has been assessed using a sensitive S1 binding titration. The equilibrium between closed and open (C to M states, KT = 0.1-0.14) was similar for all vertebrate Tms. Apart from skTm where the apparent cooperative unit size (n) is the same as the structural size (n = 7 actin sites), the other vertebrate Tms that were studied exhibited large n values (n = 12-14). The yeast Tms also exhibited large values of n (6-9) in comparison to their structural sizes (4-5). The determined value of KT depended on the N-terminal sequence (KT = 0.15-1). These results are compared with the effect of S1 upon Tm's affinity for actin. The yeast Tms have regulatory parameters similar to those of skTm, but unlike skTm, S1 has little effect upon their actin affinity. This shows that an actin state with a high affinity for S1 and Tm is not necessary for regulation, and the higher affinity of S1 for actin in the presence of vertebrate Tms is probably the result of a direct interaction of S1 with Tm.

Item Type: Article
Additional information: 0006-2960 (Print) Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S.
Uncontrolled keywords: Actins/metabolism Amino Acid Sequence Animals Genetic Vectors/biosynthesis/chemical synthesis Macromolecular Substances Models, Chemical Molecular Sequence Data Myosin Subfragments/chemistry/metabolism Peptide Fragments/*chemistry/genetics/metabolism Protein Binding/genetics Protein Isoforms/chemistry/genetics/metabolism Rats Recombinant Proteins/biosynthesis/chemistry/metabolism Saccharomyces cerevisiae/genetics Tropomyosin/*chemistry/genetics/metabolism
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences > Protein Science Group
Depositing User: Michael Geeves
Date Deposited: 29 Aug 2008 11:26
Last Modified: 21 May 2014 07:36
Resource URI: (The current URI for this page, for reference purposes)
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