Conformational Changes in the Calcium-Binding Protein of the Troponin Complex (Troponin-C) from Rabbit Skeletal Muscle

1973 ◽  
Vol 1 (4) ◽  
pp. 858-859 ◽  
Author(s):  
J. F. HEAD ◽  
S. V. PERRY
1997 ◽  
Vol 321 (3) ◽  
pp. 873-878 ◽  
Author(s):  
Alexei A. POLYAKOV ◽  
Nikolai B. GUSEV

Troponin C, a structural analogue of calmodulin, was used for mapping the calmodulin-binding sites of caldesmon. The apparent Kd values for the formation of the caldesmonŐcalcium-binding-protein complex as determined by native gel electrophoresis were 0.5, 1.2 and 3.9 ƁM for calmodulin, rabbit skeletal muscle troponin C and bovine cardiac troponin C respectively. Troponin C induced a 4Ő6 nm blue shift of the Trp fluorescence of caldesmon without affecting the amplitude of fluorescence. In the presence of Ca2+, troponin C induced partial displacement of caldesmon from actinŐtropomyosin complexes. Addition of 5,5ƀ-dithiobis(nitrobenzoic) acid to an equimolar complex of caldesmon and troponin C induced disulphide cross-linking between Cys-98 of rabbit skeletal muscle troponin C and the single Cys residue of duck gizzard caldesmon, located in a position analogous to Cys-580 of the chicken gizzard protein. The cross-linked caldesmonŐtroponin C complex was ineffective in inhibiting actomyosin ATPase activity. It is concluded that Cys-580 of caldesmon can be located close to both the central helix of calcium-binding proteins and the C-terminal domain of actin. This may be important for the regulation of actomyosin ATPase activity by caldesmon.


1979 ◽  
Vol 57 (6) ◽  
pp. 737-748 ◽  
Author(s):  
Theo Hofmann ◽  
Michiko Kawakami ◽  
Anthony J. W. Hitchman ◽  
Joan E. Harrison ◽  
Keith J. Dorrington

The complete amino acid sequence of the calcium-binding protein (CaBP) from pig intestinal mucosa has been determined: Ac-Ser-Ala-Gln-Lys-Ser-Pro-Ala-Glu-Leu-Lys-Ser-Ile-Phe-Glu-Lys-Tyr-Ala-Ala-Lys-Glu-Gly-Asp-Pro-Asn-Gln-Leu-Ser-Lys-Glu-Glu-Leu-Lys-Gln-Leu-Ile-Gln-Ala-Glu-Phe-Pro-Ser-Leu-Leu-Lys-Gly-Pro-Arg-Thr-Leu-Asp-Asp-Leu-Phe-Gln-Glu-Leu-Asp-Lys-Asn-Gly-Asn-Gly-Glu-Val-Ser-Phe-Glu-Glu-Phe-Gln-Val-Leu-Val-Lys-Lys-Ile-Ser-Gln-OH. The N-terminal octapeptide sequence was determined by mass spectrometry analysis by Morris and Dell. The first 45 residues of bovine CaBP differ only in six positions from the corresponding sequence of the porcine protein, except that the sequence starts in position two of the porcine sequence. The mammalian intestinal CaBP's belong to the troponin-C superfamily on the basis of an analysis by Barker and Dayhoff.


1973 ◽  
Vol 131 (2) ◽  
pp. 425-428 ◽  
Author(s):  
S. V. Perry ◽  
H. A. Cole

Most of the phosphorus present in the troponin complex, which on average contains 1 mol of P/80000g, is associated with the ‘37000 component’ (0.6mol of P/mol). The inhibitory protein and particularly the ‘37000 component’, but not the calcium-binding protein, were phosphorylated when incubated with phosphorylase b kinase and [γ-32P]ATP.


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