Molecular basis of cooperativity in vertebrate muscle thin filaments

Brandt, Philip W.; Diamond, Michael S.; Glück, Brigitte; Kawai, Masataka; Schachat, Fred

doi:10.1007/bf02913943

Cited by 23 publications

(13 citation statements)

References 31 publications

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“…A summary of the data from all 13 myocyte preparations studied is shown in Fig. 6 B. The right shift seen in the tension-pCa relation after partial extraction of TnC is similar to that seen previously in skeletal muscle (Brandt et al, 1984;Moss et al, 1985). With readdition of bovine cardiac TnC, Ca 2+ sensitivity returned to control levels.…”

Section: Effect Of Tnc Extraction On the Tension-pca Relationship In supporting

confidence: 79%

The effect of altered temperature on Ca2(+)-sensitive force in permeabilized myocardium and skeletal muscle. Evidence for force dependence of thin filament activation.

Sweitzer

Moss

1990

The Journal of General Physiology

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The effect of changes in temperature on the calcium sensitivity of tension development was examined in permeabilized cellular preparations of rat ventricle and rabbit psoas muscle. Maximum force and Ca 9+ sensitivity of force development increased with temperature in both muscle types. Cardiac muscle was more sensitive to changes in temperature than skeletal muscle in the range 10-15~ It was postulated that the level of thin filament activation may be decreased by cooling. To investigate this possibility, troponin C (TnC) was partially extracted from both muscle types, thus decreasing the level of thin filament activation independent of temperature and, at least in skeletal muscle fibers, decreasing cooperative activation of the thin filament as well. TnC extraction from cardiac muscle reduced the calcium sensitivity of tension less than did extraction of TnC from skeletal muscle. In skeletal muscle the midpoint shift of the tension-pCa curve with altered temperature was greater after TnC extraction than in control fibers. Calcium sensitivity of tension development was proportional to the maximum tension generated in cardiac or skeletal muscle under all conditions studied. Based on these results, we conclude that (a) maximum tension-generating capability and calcium sensitivity of tension development are related, perhaps causally, in fast skeletal and cardiac muscles, and (b) thin filament activation is less cooperative in cardiac muscle than in skeletal muscle, which explains the differential sensitivity of the two fiber types to temperature and TnC extraction. Reducing thin filament cooperativity in skeletal muscle by TnC extraction results in a response to temperature similar to that of control cardiac cells. This study provides evidence that force levels in striated muscle influence the calcium binding affinity of TnC.Address reprint requests to Dr.

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Section: Effect Of Tnc Extraction On the Tension-pca Relationship In supporting

confidence: 79%

The effect of altered temperature on Ca2(+)-sensitive force in permeabilized myocardium and skeletal muscle. Evidence for force dependence of thin filament activation.

Sweitzer

Moss

1990

The Journal of General Physiology

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“…7). In addition, the threshold for tension production in ALD fibres (Brandt et al 1984;Moss, Giulian & Greaser, 1985 other than the stoichiometric ratio of TnC to other contractile proteins at this age.…”

Section: Neonatal Muscle Fibresmentioning

confidence: 94%

“…The tension generated by the neonatal ALD fibres is significantly less (P < 0-005) than that generated by the neonatal PM and PLD fibres and by the adult ALD fibres. Previous studies have demonstrated that the tension-pCa relationship for muscle fibres deficient in TnC is shifted to lower pCas relative to the curve for fibres with the normal complement of TnC and that TnC-deficient fibres also generate less than normal tension during maximal calcium activation (Brandt et al 1984;Moss, Giulian & Greaser, 1985). It was therefore necessary to test whether the shifts in the tension-pCa curve between neonatal and adult PM and PLD fibres were related to the relatively low PO/CSA of neonatal fibres compared to adult fibres, under the assumption that the low tension reflected a deficiency in TnC.…”

Section: Neonatal Muscle Fibresmentioning

confidence: 98%

“…Tobacman (1988) reported that removal of the aminoterminal 38 amino acids from bovine cardiac TnT by chemical cleavage also modifies the Ca2" sensitivity of thin filament-activated subfragment-1 MgATPase activity. The Ca2" sensitivities of tension production in skinned fibres from several fast muscles of adult rabbit correlate with specific TnT and Tm combinations which vary among the individual fibres (Brandt, Diamond, Gluck, Kawai & Schachat, 1984;Schachat, Diamond & Brandt, 1987).…”

Section: Introductionmentioning

confidence: 99%

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Developmental changes in troponin T isoform expression and tension production in chicken single skeletal muscle fibres.

Reiser

Greaser

Moss

1992

The Journal of Physiology

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SUMMARY1. The Ca2" sensitivity of tension development was characterized in single skinned fibres from the slow anterior latissimus dorsi (ALD), fast posterior latissimus dorsi (PLD), and fast pectoralis major (PM) muscles of the chicken at adult and neonatal (2 weeks post-hatch) stages of development. In the adult, the PM was most sensitive, the ALD intermediate, and the PLD least sensitive to Ca2 .2. PM and PLD fibres were less sensitive to Ca2`at the neonatal stage of development than in the adult. However, ALD fibres exhibited no age-dependent changes in Ca2+ sensitivity. 3. Characterization of regulatory protein composition indicated that the PM and PLD fibres had identical fast isoforms of troponin C and troponin I at each developmental stage examined, but there were muscle-specific and age-dependent expressions of troponin T isoforms in these fibres.4. In the ALD fibres, identical slow isoforms of troponin C, troponin I and tropomyosin were found at each stage. In addition, the troponin T isoform that was present did not change with age.5. The results suggest a relationship between the specifie troponin T isoform composition of individual muscle fibres and their calcium sensitivities of tension development.

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“…Endogenous TnC from barnacle myofibrillar bundles was removed by incubation with a low ionic strength 2 mM Na 2 EDTA solution, a widely used extraction technique previously shown to selectively remove TnC from both vertebrate striated muscle fibres [7,8,23,29,44] and barnacle myofibrillar bundles [2,3,4,5,6,14,36]. In vertebrate striated muscle EDTA is thought to act by removing the Mg 2+ ions from the Ca 2+ /Mg 2+ sites (III and IV), thereby causing the dissociation of TnC from the thin filament TnI.…”

Section: Discussionmentioning

confidence: 99%

Characterisation of a mutant of barnacle troponin C lacking Ca 2+ -binding sites at positions II and IV

Allhouse¹,

Guzman

Miller

et al. 1999

Pfl�gers Archiv European Journal of Physiology

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This study investigates a mutant barnacle troponin C (TnC) protein (BTnC2-4-) in which the Ca2+-binding sites (sites II and IV) have been rendered non-functional. Eliminating Ca2+ binding at both Ca2+-binding sites of barnacle TnC did not prevent the incorporation of BTnC2-4- into TnC-depleted myofibrillar bundles, although, as expected, the mutant was not able to effect muscle regulation. We conclude that the Mg2+ involved in stabilising the interaction between TnC and TnI in the barnacle must bind at a separate location to the Ca2+-binding sites. Competition experiments between BTnC2-4- and wild-type barnacle TnC (BTnCWT) or the native isoform BTnC2 indicate that BTnC2-4- has an approximately fourfold higher affinity for barnacle TnI than BTnCWT but a lower affinity for TnI compared to BTnC2. These results indicate that disabling sites II and IV changes the affinity of BTnC2-4- for TnC-denuded barnacle myofibrils, altering the stability of the bond formed between TnC and the thin filament.

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Molecular basis of cooperativity in vertebrate muscle thin filaments

Cited by 23 publications

References 31 publications

The effect of altered temperature on Ca2(+)-sensitive force in permeabilized myocardium and skeletal muscle. Evidence for force dependence of thin filament activation.

The effect of altered temperature on Ca2(+)-sensitive force in permeabilized myocardium and skeletal muscle. Evidence for force dependence of thin filament activation.

Developmental changes in troponin T isoform expression and tension production in chicken single skeletal muscle fibres.

Characterisation of a mutant of barnacle troponin C lacking Ca 2+ -binding sites at positions II and IV

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