Glutamine Residue at 276 of smooth muscle α-tropomyosin is primarily responsible for higher actin affinity

Jung, Sun-Ju; Cho, Young-Joon

doi:10.5352/jls.2007.17.2.204

Cited by 1 publication

(2 citation statements)

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“…Actin affinity of TM19(QA) was approximately 1.5 times and 6 times higher than that of TM23(CA) and TM10(HA), respectively. The fact that TM19(QA) was much higher than TM10(HA) was consistent with previous report that Gln(Q) at 276 in smooth muscle α-tropomyosin was primarily responsible for higher actin affinity, implying the importance of residue 276 on actin affinities [22]. The result that unacetylated TM24(QC) showed approximately 5 times lower actin affinity than unacetylated TM19(QA) suggested that the presence of Cys at 277 was attributed to lower actin affinity of unacetylated TM24(QC).…”

Section: Actin Affinities Of Unacetylated Mutant Tropomyosinssupporting

confidence: 92%

“…It has been indicated that local changes at the amino terminus greatly influence the actin affinity [6,7,32]. It has been also reported that carboxyl terminal 9 amino acid residues define actin affinity of tropomyosin [4,17] and among 9 residues the residues 276 and 277 of the carboxyl terminal region are important for actin affinity [5,22].…”

Section: Introductionmentioning

confidence: 99%

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Actin Affinities of Recombinant α-Tropomyosins That Residues 276 or 277 in the Carboxyl Terminal Region are Individually Substituted to a Cysteine Residue

2009

Journal of Life Science

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It has been previously reported that the carboxyl terminal residues 276 and 277 of α-tropomyosin are important for actin affinity. In order to investigate actin affinities of these two residues of skeletal (HA) and smooth (QT) muscle α-tropomyosins, a series of mutant tropomyosins were constructed in which residues at either 276 or 277 were individually replaced with a cysteine residue for chemical modification. These mutants were overexpressed in E. coli as unacetylated and Ala-Ser (AS) dipeptide fusion forms. While actin affinities of unacetylated tropomyosins were considerably low, those of AS/TMs were remarkably higher than those of corresponding unacetylated tropomyosins. However, actin affinities of AS/TM24 (QC) and AS/TM29 (HC) were dramatically lower than those of other AS/TMs and were close to those of unacetylated tropomyosins. In addition, actin affinities of unacetylated TM24 (QC) and TM29 (HC) failed to be restored in the presence of troponin, unlike unacetylated TM10 (HA) and TM23 (CA). These results indicated that the presence of a cysteine residue at 277 caused a drastic decrease in actin affinity, and also that the residue 277 is important for actin affinity of α-tropomyosin. Since TM23 (CA) showed high actin affinity, it may serve as a valuable tool for chemical modification studies for investigating the interaction of the carboxyl terminal residues of α-tropomyosin with actin and/or troponin.

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Section: Actin Affinities Of Unacetylated Mutant Tropomyosinssupporting

confidence: 92%