scholarly journals Characterization of a region of the primary sequence of troponin C involved in calcium ion-dependent interaction with troponin I

1978 ◽  
Vol 173 (2) ◽  
pp. 449-457 ◽  
Author(s):  
R A Weeks ◽  
S V Perry
Keyword(s):  
Skeletal Muscle ◽  
Troponin I ◽  
Gel Filtration ◽  
Troponin C ◽  
Fast Skeletal Muscle ◽  
Dependent Protein Kinase ◽  
Mechanism Of Interaction ◽  
Dependent Protein ◽  
Dependent Interaction

1. The CNBr digest of troponin C from rabbit fast skeletal muscle was shown to possess many of the functional properties of the whole troponin C molecule. 2. A peptide corresponding to residues 83-134 was isolated, which forms a Ca(2+-dependent complex with troponin I and neutralizes the inhibition by troponin I of the Mg(2+-stimulated adenosine triphosphatase of desensitized actomyosin. 3. The peptide inhibits the phosphorylation of fast-skeletal-muscle, but not cardiac-muscle, troponin I, by 3′ :5′-cyclic AMP-dependent protein kinase. In this property it was as effective as whole skeletal-muscle troponin C when compared on a molar basis. 4. Biological activity was also present in other fractions obtained from the CNBr digest. 5. By gel filtration and affinity chromatography of the whole CNBr digest of troponin C, two peptides, one of which was identified as representing residues 83-134, were shown to form Ca(2+-dependent complexes with troponin I. 6. The significance of these findings for the mechanism of interaction of troponin C and troponin I is discussed.

scholarly journals The phosphorylation of troponin I from cardiac muscle

1975 ◽  
Vol 149 (3) ◽  
pp. 525-533 ◽  
Author(s):  
H A Cole ◽  
S V Perry
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Cardiac Muscle ◽  
Cardiac Troponin ◽  
Troponin I ◽  
Cardiac Troponin I ◽  
Phosphorylase Kinase ◽  
Dependent Protein Kinase ◽  
Dependent Protein

1. Troponin I isolated from fresh cardiac muscle by affinity chromatography contains about 1.9 mol of covalently bound phosphate/mol. Similar preparations of white-skeletal-muscle troponin I contain about 0.5 mol of phosphate/mol. 2. A 3':5'-cyclic AMP-dependent protein kinase and a protein phosphatase are associated with troponin isolated from cardiac muscle. 3. Bovine cardiac 3':5'-cyclic AMP-dependent protein kinase catalyses the phosphorylation of cardiac troponin I 30 times faster than white-skeletal-muscle troponin I. 4. Troponin I is the only component of cardiac troponin phosphorylated at a significant rate by the endogenous or a bovine cardiac 3':5'-cyclic AMP-dependent protein kinase. 5. Phosphorylase kinase catalyses the phosphorylation of cardiac troponin I at similar or slightly faster rates than white-skeletal-muscle troponin I. 6. Troponin C inhibits the phosphorylation of cardiac and skeletal troponin I catalysed by phosphorylase kinase and the phosphorylation of white skeletal troponin I catalysed by 3':5'-cyclic AMP-dependent protein kinase; the phosphorylation of cardiac troponin I catalysed by the latter enzyme is not inhibited.

scholarly journals Preparation and characterization of bovine aortic actin

1985 ◽  
Vol 228 (2) ◽  
pp. 433-441 ◽  
Author(s):  
J C Cavadore ◽  
C Axelrud-Cavadore ◽  
P Berta ◽  
M C Harricane ◽  
J Haiech
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle Actin ◽  
Original Method ◽  
Muscle Actin ◽  
Dependent Protein Kinase ◽  
Skeletal Muscle Myosin ◽  
Tryptophan Residues ◽  
Dependent Protein ◽  
Muscle Myosin

A functional vascular smooth-muscle actin from bovine aorta was purified to homogeneity by an original method and was able to polymerize. Aortic actin is composed of two major isoforms and at least two minor ones. This actin was not phosphorylated by either cyclic AMP-dependent protein kinase or C kinase. The physical properties of aortic actin were found to be very similar to those of skeletal-muscle actin, except for amino acid composition (three tryptophan residues instead of four). The aortic actin and skeletal-muscle actin differ in the extent of activation of the Mg-dependent ATPase of skeletal-muscle myosin.

The binding sites of rabbit skeletal troponin-I on troponin-T

1980 ◽  
Vol 58 (8) ◽  
pp. 649-654 ◽  
Author(s):  
Joyce R. Pearlstone ◽  
Lawrence B. Smillie
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Binding Site ◽  
Binding Sites ◽  
Troponin I ◽  
Troponin T ◽  
Gel Filtration ◽  
Troponin C ◽  
Separate Site

Various fragments derived from rabbit skeletal muscle troponin-T (Tn-T) by chemical and (or) proteolytic cleavage were mixed with whole troponin-I (Tn-I) and applied to a Sephadex G-75 gel filtration column in order to determine the binding site of Tn-I on Tn-T. This site of interaction was found to span two distinct regions of Tn-T. The first site involves the highly acidic NH2-terminal fragment CB3 (residues 1–70 of Tn-T). A second separate site is located in the region of residues 152–209 of Tn-T. The present study, in conjunction with our earlier work on tropomyosin – Tn-T binding and Tn-T – troponin-C binding, depicts Tn-T as being a functionally efficient molecule composed of several distinct domains of specialized amino acid sequence, each of which carries out a role in the binding of a different protein.

scholarly journals Phosphorylation of troponin and the effects of interactions between the components of the complex

1974 ◽  
Vol 141 (3) ◽  
pp. 733-743 ◽  
Author(s):  
Samuel V. Perry ◽  
Heather A. Cole
Keyword(s):  
Protein Kinase ◽  
Troponin I ◽  
Troponin T ◽  
Troponin C ◽  
Phosphorylase Kinase ◽  
Significant Extent ◽  
Dependent Protein Kinase ◽  
Prolonged Incubation ◽  
Troponin Complex ◽  
Dependent Protein

1. The troponin complex from skeletal muscle contains approximately 1 mol of phosphate/80000g of complex, covalently bound to the troponin T component. 2. On prolonged incubation of the troponin complex or troponin T with phosphorylase kinase the phosphate content of troponin T was increased to approx. 3mol/mol. 3. On prolonged incubation of troponin I with phosphorylase kinase up to 1.6mol of phosphate/mol were incorporated. 4. Phosphorylation of troponin I was greatly inhibited by troponin C owing to the strong interaction between these proteins. Thus in the troponin complex troponin T was the main substrate for phosphorylase kinase. The phosphorylation of isolated troponin T was also inhibited by troponin C. 5. Troponin I was phosphorylated when the troponin complex was incubated with a bovine cardiac 3′:5′-cyclic AMP-dependent protein kinase. Troponin T either in its isolated form or in the troponin complex was not phosphorylated by bovine protein kinase to any significant extent under the conditions used. 6. If the troponin complex was dephosphorylated to 0.2mol/mol, or phosphorylated up to 2.5mol/mol there was no significant effect on the ability of normal concentrations to confer Ca2+sensitivity on the adenosine triphosphatase of densensitized actomyosin.

scholarly journals Purification and characterization of two wheat-embryo protein phosphatases

1988 ◽  
Vol 251 (2) ◽  
pp. 357-363 ◽  
Author(s):  
G M Polya ◽  
M Haritou
Keyword(s):  
Protein Phosphatase ◽  
Wheat Germ ◽  
Protein Phosphatases ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Dependent Protein Kinase ◽  
Wheat Embryo ◽  
Dependent Protein ◽  
Enzyme I

Two protein phosphatases (enzymes I and II) were extensively purified from wheat embryo by a procedure involving chromatography on DEAE-cellulose, phenyl-Sepharose CL-4B, DEAE-Sephacel and Ultrogel AcA 44. Preparations of enzyme I (Mr 197,000) are heterogeneous. Preparations of enzyme II (Mr 35,000) contain only one major polypeptide (Mr 17,500), which exactly co-purifies with protein phosphatase II on gel filtration and is not present in preparations of enzyme I. However, this major polypeptide has been identified as calmodulin. Calmodulin and protein phosphatase II can be separated by further chromatography on phenyl-Sepharose CL-4B. Protein phosphatases I and II do not require Mg2+ or Ca2+ for activity. Both enzymes catalyse the dephosphorylation of phosphohistone H1 (phosphorylated by wheat-germ Ca2+-dependent protein kinase) and of phosphocasein (phosphorylated by wheat-germ Ca2+-independent casein kinase), but neither enzyme dephosphorylates a range of non-protein phosphomonoesters tested. Both enzymes are inhibited by Zn2+, Hg2+, vanadate, molybdate, F-, pyrophosphate and ATP.

scholarly journals Phosphorylation of skeletal-muscle troponin I and troponin T by phospholipid-sensitive Ca2+-dependent protein kinase and its inhibition by troponin C and tropomyosin

1984 ◽  
Vol 218 (2) ◽  
pp. 361-369 ◽  
Author(s):  
G J Mazzei ◽  
J F Kuo
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Cardiac Troponin ◽  
Troponin I ◽  
Troponin T ◽  
Troponin C ◽  
Cardiac Troponin I ◽  
Equimolar Amount ◽  
Dependent Protein Kinase ◽  
Dependent Protein

Skeletal-muscle troponin I and troponin T were found to be rapidly phosphorylated by cardiac phospholipid-sensitive Ca2+-dependent protein kinase, with Km values of 6.66 and 0.13 microM respectively. Stoichiometric phosphorylation of skeletal troponin I (endogenous phosphate content 0.7 mol/mol) indicated that the Ca2+-dependent enzyme and cyclic AMP-dependent protein kinase incorporated 0.9 and 0.8 mol/mol respectively. The same experiments with skeletal troponin T (endogenous phosphate content 1.9 mol/mol) revealed a maximal phosphorylation of 2 mol/mol by the Ca2+-dependent enzyme, whereas the cyclic AMP-dependent enzyme was unable to phosphorylate troponin T. The Ca2+-dependent enzyme phosphorylated both serine and threonine residues in skeletal and cardiac troponin I or troponin T; the cyclic AMP-dependent enzyme, in comparison, phosphorylated only serine in skeletal and cardiac troponin I. Although an equimolar amount of skeletal or cardiac troponin C markedly inhibited (80-90%) phosphorylation of skeletal and cardiac troponin I by the Ca2+-dependent enzyme, these troponin C preparations inhibited only phosphorylation of skeletal troponin I, but not that of cardiac troponin I, by the cyclic AMP-dependent enzyme. Calmodulin and Ca2+-binding protein S-100a could mimic the inhibitory effect of troponin C. A tissue specificity appeared to exist for the skeletal troponin T-skeletal troponin C interaction. Inhibition of troponin T phosphorylation by an equimolar amount of troponin C was lower than that of troponin I phosphorylation; these findings might explain in part why troponin T was the major substrate for the Ca2+-dependent enzyme in the troponin complex. The present studies indicate that skeletal and cardiac troponin I and troponin T were effective substrates for phospholipid-sensitive Ca2+-dependent protein kinase, suggesting a potential involvement of this Ca2+-effector enzyme in the regulation of myofibrillar activity.

Sign in / Sign up

Export Citation Format

Share Document