Biomaterial Database

Active site-directed inhibition of Ca2+/calmodulin-dependent protein kinase type II by a bifunctional calmodulin-binding peptide. 1988

P T Kelly, and R P Weinberger, and M N Waxham

Department of Neurobiology, University of Texas Health Science Center, Houston 77225.

The activation of Ca2+/calmodulin (CaM)-dependent protein kinase II (CaM-KII) by Ca2+/CaM results in autophosphorylation and the generation of Ca2+/CaM-independent enzyme activity. We postulated that CaM binding and subsequent autophosphorylation alters the conformation of CaM-KII and exposes its substrate-binding and catalytic site(s). Previous peptide mapping studies on CaM-KII demonstrated the close proximity of CaM-binding and autophosphorylation domains. Analyses of the deduced amino acid sequences encoding CaM-KII have allowed the identification of its CaM-binding domain and have revealed two consensus phosphorylation sites that flank this regulatory domain. We report herein the distinct properties of two synthetic peptides modeled after the CaM-binding domain of CaM-KII. The first peptide binds CaM in a Ca2+-dependent manner and is an antagonist of CaM-KII activation (IC50 approximately equal to 75 nM). It does not, however, inhibit CaM-KII activity. A second peptide containing the same CaM-binding domain plus a putative autophosphorylation sequence at its N terminus displayed bifunctional regulatory properties. In addition to being a CaM antagonist, the latter was a potent inhibitor of Ca2+/CaM-independent kinase activity (IC50 approximately equal to 2 microM). We suggest that this bifunctional peptide represents an active site-directed inhibitory element of CaM-KII. The separation of CaM antagonist and active site-directed inhibitory properties of this peptide distinguishes CaM-KII from other CaM-dependent enzymes in which bifunctional regulatory properties appear to reside in the same peptide domain. These results indicate that the definition of site-directed inhibitory peptides should, in some cases, be expanded to include bona fide phosphorylation sites.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009419	Nerve Tissue Proteins		Proteins, Nerve Tissue,Tissue Proteins, Nerve
D010455	Peptides	Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS.	Peptide,Polypeptide,Polypeptides
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
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
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
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining