The amino acid sequence of bovine cardiac troponin-C. Comparison with rabbit skeletal troponin-C

Cardiac myofibrils isolated from trout heart have been demonstrated to have a higher sensitivity for Ca2+ than mammalian cardiac myofibrils. Using cardiac troponin C (cTnC) cloned from trout and mammalian hearts, we have previously demonstrated that this comparatively high Ca2+ sensitivity is due, in part, to trout cTnC (ScTnC) having twice the Ca2+ affinity of mammalian cTnC (McTnC) over a broad range of temperatures. The amino acid sequence of ScTnC is 92% identical to McTnC. To determine the residues responsible for the high Ca2+ affinity, the function of a number of ScTnC and McTnC mutants was characterized by monitoring an intrinsic fluorescent reporter that monitors Ca2+ binding to site II (F27W). The removal of the COOH terminus (amino acids 90–161) from ScTnC and McTnC maintained the difference in Ca2+ affinity between the truncated cTnC isoforms (ScNTnC and McNTnC). The replacement of Gln29 and Asp30 in ScNTnC with the corresponding residues from McNTnC, Leu and Gly, respectively, reduced Ca2+ affinity to that of McNTnC. These results demonstrate that Gln29 and Asp30 in ScTnC are required for the high Ca2+ affinity of site II.

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[27] The Cloning and the codon and amino acid sequence of the quail slow/cardiac troponin C cDNA

Methods in Enzymology - Cellular Regulators Part A: Calcium- and Calmodulin-Binding Proteins ◽

10.1016/0076-6879(87)39096-2 ◽

1987 ◽

pp. 326-337 ◽

Cited By ~ 11

Author(s):

Peter C. Maisonpierre ◽

Kenneth E.M. Hastings ◽

Charles P. Emerson

Keyword(s):

Amino Acid ◽

Amino Acid Sequence ◽

Cardiac Troponin ◽

Troponin C ◽

Cardiac Troponin C

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Determination of the complete amino acid sequence of bovine cardiac troponin C

Biochemistry ◽

10.1021/bi00650a033 ◽

1976 ◽

Vol 15 (5) ◽

pp. 1171-1180 ◽

Cited By ~ 190

Author(s):

Jean P. Van Eerd ◽

Kenji Takahashi

Keyword(s):

Amino Acid ◽

Amino Acid Sequence ◽

Cardiac Troponin ◽

Troponin C ◽

Complete Amino Acid Sequence ◽

Cardiac Troponin C

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The amino acid sequence of human cardiac troponin-C

Muscle & Nerve ◽

10.1002/mus.880090112 ◽

1986 ◽

Vol 9 (1) ◽

pp. 73-77 ◽

Cited By ~ 21

Author(s):

Alex Roher ◽

Norman Lieska ◽

Werner Spitz

Keyword(s):

Amino Acid ◽

Amino Acid Sequence ◽

Cardiac Troponin ◽

Troponin C ◽

Cardiac Troponin C ◽

Human Cardiac Troponin C

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Increasing mammalian cardiomyocyte contractility with residues identified in trout troponin C

Physiological Genomics ◽

10.1152/physiolgenomics.00007.2005 ◽

2005 ◽

Vol 22 (1) ◽

pp. 1-7 ◽

Cited By ~ 22

Author(s):

Todd E. Gillis ◽

Bo Liang ◽

Franca Chung ◽

Glen F. Tibbits

Keyword(s):

Amino Acid ◽

Cardiac Myocytes ◽

Cardiac Troponin ◽

Troponin C ◽

Force Generation ◽

Wild Type ◽

Cardiac Troponin C ◽

Cardiomyocyte Contractility

The Ca2+ sensitivity of force generation in trout cardiac myocytes is significantly greater than that from mammalian hearts. One mechanism that we have suggested to be responsible, at least in part, for this high Ca2+ sensitivity is the isoform of cardiac troponin C (cTnC) found in trout hearts (ScTnC), which has greater than twice the Ca2+ affinity of mammalian cTnC (McTnC). Here, through a series of mutations, the residues in ScTnC responsible for its high Ca2+ affinity have been identified as being Asn2, Ile28, Gln29, and Asp30. When these residues in McTnC were mutated to the trout-equivalent amino acid, the Ca2+ affinity of the molecule, determined by monitoring the fluorescence of a Trp inserted for a Phe at residue 27, is comparable to that of ScTnC. To determine how a McTnC mutant containing Asn2, Ile28, Gln29, and Asp30 (NIQD McTnC) affects the Ca2+ sensitivity of force generation, endogenous cTnC in single, chemically skinned rabbit cardiomyocytes was replaced with either wild-type McTnC or NIQD McTnC. Our results demonstrate that the cardiomyocytes containing NIQD McTnC were approximately twice as sensitive to Ca2+, illustrating that a McTnC mutant with similar Ca2+ affinity as ScTnC can be used to sensitize mammalian cardiac myocytes to Ca2+.

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