Biomaterial Database

Calmodulin antagonist action in smooth-muscle myosin phosphorylation. Different mechanisms for trifluoperazine and calmidazolium inhibition. 1989

A Sobieszek

Institute of Molecular Biology, Austrian Academy of Sciences, Salzburg.

The mechanism of inhibition of myosin phosphorylation by calmodulin antagonists [trifluoperazine (TFP) and calmidazolium (CAL)] was investigated in two enzyme-substrate systems: (1) mixtures of isolated myosin phosphorylatable light-chain (L20), myosin light-chain kinase (MCLKase) and calmodulin (CM); (2) synthetic self-assembled myosin filaments containing tightly bound endogenous MLCKase and CM. Double-reciprocal plots obtained with the first system were non-linear, indicating that the antagonists did not act exclusively on CM to inhibit MLCKase. First-order phosphorylation progress curves obtained at different CM antagonist concentrations for the more native filamentous myosin system indicated that the antagonists could also inhibit phosphorylation by interaction with the myosin phosphorylation site. Further analysis of these data in accordance with Reiner [(1969) Behavior of Enzyme Systems, 2nd edn., pp. 185-201, Van Nostrand-Reinhold, New York] showed that over a range of concentrations required to inhibit phosphorylation TFP interacted with free CM as well as with the myosin phosphorylation site: accordingly inhibition was of an activator- and substrate-depletion type. CAL inhibition was more CM-specific and operated via an activator-combination mechanism, inhibiting free CM as well as the CM-MLCKase complex. Both CM and the isolated L20 light chain antagonized the inhibitory effects of CAL and TFP, consistent with the above analysis.

UI	MeSH Term	Description	Entries
D007093	Imidazoles	Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D009218	Myosins	A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.	Myosin ATPase,ATPase, Actin-Activated,ATPase, Actomyosin,ATPase, Myosin,Actin-Activated ATPase,Actomyosin ATPase,Actomyosin Adenosinetriphosphatase,Adenosine Triphosphatase, Myosin,Adenosinetriphosphatase, Actomyosin,Adenosinetriphosphatase, Myosin,Myosin,Myosin Adenosinetriphosphatase,ATPase, Actin Activated,Actin Activated ATPase,Myosin Adenosine Triphosphatase
D009219	Myosin-Light-Chain Kinase	An enzyme that phosphorylates myosin light chains in the presence of ATP to yield myosin-light chain phosphate and ADP, and requires calcium and CALMODULIN. The 20-kDa light chain is phosphorylated more rapidly than any other acceptor, but light chains from other myosins and myosin itself can act as acceptors. The enzyme plays a central role in the regulation of smooth muscle contraction.	Myosin Kinase,Myosin LCK,Myosin Regulatory Light-Chain Kinase,Kinase, Myosin,Kinase, Myosin-Light-Chain,LCK, Myosin,Myosin Light Chain Kinase,Myosin Regulatory Light Chain Kinase
D010766	Phosphorylation	The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.	Phosphorylations
D002147	Calmodulin	A heat-stable, low-molecular-weight activator protein found mainly in the brain and heart. The binding of calcium ions to this protein allows this protein to bind to cyclic nucleotide phosphodiesterases and to adenyl cyclase with subsequent activation. Thereby this protein modulates cyclic AMP and cyclic GMP levels.	Calcium-Dependent Activator Protein,Calcium-Dependent Regulator,Bovine Activator Protein,Cyclic AMP-Phosphodiesterase Activator,Phosphodiesterase Activating Factor,Phosphodiesterase Activator Protein,Phosphodiesterase Protein Activator,Regulator, Calcium-Dependent,AMP-Phosphodiesterase Activator, Cyclic,Activating Factor, Phosphodiesterase,Activator Protein, Bovine,Activator Protein, Calcium-Dependent,Activator Protein, Phosphodiesterase,Activator, Cyclic AMP-Phosphodiesterase,Activator, Phosphodiesterase Protein,Calcium Dependent Activator Protein,Calcium Dependent Regulator,Cyclic AMP Phosphodiesterase Activator,Factor, Phosphodiesterase Activating,Protein Activator, Phosphodiesterase,Protein, Bovine Activator,Protein, Calcium-Dependent Activator,Protein, Phosphodiesterase Activator,Regulator, Calcium Dependent
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D014268	Trifluoperazine	A phenothiazine with actions similar to CHLORPROMAZINE. It is used as an antipsychotic and an antiemetic.	Trifluoroperazine,Triftazin,Apo-Trifluoperazine,Eskazine,Flupazine,Stelazine,Terfluzine,Trifluoperazine HCL,Trifluoperazine Hydrochloride,Trifluperazine,Apo Trifluoperazine,ApoTrifluoperazine