Cross innervation and the regulatory protein system of rabbit soleus muscle

Amphlett, Godfrey W.; Perry, S. V.; Syska, H.; Brown, Margaret D.; Vrbová, Gerta

doi:10.1038/257602a0

Cited by 74 publications

(21 citation statements)

References 16 publications

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“…Moreover, considerable reported evidence supports the notion that fast muscles are richer in a-tropomyosin. In contrast, the a/fl ratio of crossinnervated rabbit soleus muscle remained unchanged, even though troponin I slow was largely replaced by troponin I fast (Amphlett et al, 1975), a finding more consistent with the present results. In resolving these differences, single-fibre analysis techniques might be very useful.…”

Section: Discussionsupporting

confidence: 92%

Electrophoretic analysis of proteins from single bovine muscle fibres

Young¹,

Davey²

1981

Biochemical Journal

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A number of single fibres were isolated by dissection of four bovine masseter (ma) muscles, three rectus abdominis (ra) muscles and eight sternomandibularis (sm) muscles. By histochemical criteria these muscles contain respectively, solely slow fibres (often called type I), predominantly fast fibres (type II), and a mixture of fast and slow. The fibres were analysed by conventional sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and the gels stained with Coomassie Blue. Irrespective of the muscle, every fibre could be classed into one of two broad groups based on the mobility of proteins in the range 135000-170000 daltons. When zones containing myosin heavy chain were cut from the single-fibre gel tracks and ‘mapped’ [Cleveland, Fischer, Kirschner & Laemmli (1977) J. Biol. Chem. 252, 1102-1106] with Staphylococcus proteinase, it was found that one group always contained fast myosin heavy chain, whereas the second group always contained the slow form. Moreover, a relatively fast-migrating alpha-tropomyosin was associated with the fast myosin group and a slow-migrating form with the slow myosin group. All fibres also contained beta-tropomyosin; the coexistence of alpha- and beta-tropomyosin is at variance with evidence that alpha-tropomyosin is restricted to fast fibres [Dhoot & Perry (1979) Nature (London) 278, 714-718]. Fast fibres containing the expected fast light chains and troponins I and C fast were identified in the three ra muscles, but in only four sm muscles. In three other sm muscles, all the fast fibres contained two troponins I and an additional myosin light chain that was more typical of myosin light chain 1 slow. The remaining sm muscle contained a fast fibre type that was similar to the first type, except that its myosin light chain 1 was more typical of the slow polymorph. Troponin T was bimorphic in all fast fibres from a ra muscles and in at least some fast fibres from one sm muscle. Peptide ‘mapping’ revealed two forms of fast myosin heavy chain distributed among fast fibres. Each form was associated with certain other proteins. Slow myosin heavy chain was unvarying in three slow fibre types identified. Troponin I polymorphs were the principal indicator of slow fibre types. The myofibrillar polymorphs identified presumably contribute to contraction properties, but beyond cud chewing involving ma muscle, nothing is known of the conditions that gave rise to the variable fibre composites in sm and ra muscles.

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Section: Discussionsupporting

confidence: 92%

Electrophoretic analysis of proteins from single bovine muscle fibres

Young¹,

Davey²

1981

Biochemical Journal

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“…The findings reported here, taken with the results of the cross innervation studies reported elsewhere [3] indicate that different mechanisms are involved in the control of the expression of the genes regulating the synthesis in skeletal muscle of the two forms of troponin I on one hand and a and /3 tropomyosin on the other. Whereas the proportions of the fast and slow muscle forms of troponin I present in adult rabbit soleus muscle are changed by increasing the speed of contraction, there is no corresponding change in troponin I composition during development of a fast skeletal muscle from the foetal to the adult form despite the increase in speed of contraction that occurs during this period (see [8] for review).…”

Section: Resultsmentioning

confidence: 78%

“…Although this change parallels the increase in speed that accompanies development in the longissimus dorsi, in the soleus muscle, for example, a similar change can not be induced by increasing the speed by cross innervation [3]. The fact that fl tropomyosin appears to be the main form present in longissimus dorsi muscle of the foetal rabbit indicates that the dimer fi2 must exist in rabbit foetal muscle.…”

Section: Resultsmentioning

confidence: 91%

“…The forms of troponin I present were identified by electrophoresis on 8% acrylamide, 6 M urea, 25 mM Tris-80 mM glycine, pH 8.6 in the presence of at least 1.5 times molar excess of troponin C from white skeletal muscle of the rabbit [2,3]. Under these conditions troponin I migrates as the troponin I-troponin C complex which has a mobility characteristic for each of the forms of troponin I.…”

Section: Electrophoresismentioning

confidence: 99%

“…It has been shown that two different forms of troponin I are present in rabbit skeletal muscle, one of which is characteristic of fast skeletal muscle and the other being the main form present in slow skeletal muscle [2,3]. Differences also exist in the tropomyosin present in the two muscle types in that the ratio of the molar amounts of the (Y and fi subunits of tropomyosin is 3.8: 1 in a fast muscle such as psoas but only 1.1: 1 in a slow muscle such as the soleus [4].…”

Section: Introductionmentioning

confidence: 99%

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