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. Author manuscript; available in PMC: 2012 Dec 16.
Published in final edited form as: J Mol Biol. 2011 Oct 20;414(5):667–680. doi: 10.1016/j.jmb.2011.10.026

Table 2.

Description of tropomyosin mutants used in the study

Tropomyosin1 Description Length Ref.
wtTm Recombinant rat striated α-Tm 284 residues 11
Δ2Tm2,3 Deletion of period 2, residues 47–88 242 residues 27
Δ3Tm2 Deletion of period 3, residues 89–123 249 residues 28
Δ6Tm2,3 Deletion of period 6, residues 208–242 249 residues 12
P2sTm4 Y60A, L64A. Generation of an additional Ala cluster within proposed period 2 actin binding site 284 residues 24
P3sTm4 L106A, A120L. Generation of an additional Ala cluster within proposed period 3 actin binding site. 284 residues 24
P2P3sTm4 L60A, L64A, L106A, A120L. Generation of additional clusters within periods 2 and 3. 284 residues 24
P1P55 Replacement of residues 165–188 in period 5 with residues 4–27, the homologous residues in period 1. Duplication of period 1. 284 residues 18

Notes:

1

All proteins were expressed in E. coli. The N-terminal Met is unacetylated.

2

The seven periods are those defined by the model in Phillips 9. The model differs from that of McLachlan and Stewart 10 in that it considers the supercoiled coiled coil structure. The periods are all multiples of seven but differ in length, being 35 or 42 residues, with the average being 38 2/3 residues, as in McLachlan and Stewart. Period 2 has 42 residues in the Phillips model.

3

Periods 3 and 6 have 35 residues in the Phillips model. Deletions of 35 residues (89–123) or 42 residues (89–130) from this area had equivalent effects on the Kapp and cooperativity of binding to actin 28.

4

Periods 1 and 5 have Ala clusters within proposed actin recognition motifs. The shift mutants create or relocate Ala clusters in periods 2 and 3 in positions homologous to those in periods 1 and 5.

5

Residues 165–188 contain the motif Phillips 9 proposed is important for actin binding, and the rest of the Ala cluster. Singh and Hitchcock-DeGregori 23 provided support for the model and showed this region is critical for actin binding. Period 1 (residues 4–27) is the only other period to have an Ala cluster in the same relationship as in period 5.