Biomaterial Database

Endogenous cleavage of phospholipase C-beta 3 by agonist-induced activation of calpain in human platelets. 1995

Y Banno, and S Nakashima, and T Hachiya, and Y Nozawa

Department of Biochemistry, Gifu University School of Medicine, Japan.

Two membrane-associated phosphoinositide-specific phospholipase Cs (mPI-PLC-1 and mPI-PLC-2) and a cytosolic enzyme (cPI-PLC) that were activated by brain G-protein beta gamma subunits have been isolated from human platelets. The truncation of mPI-PLC-1 that was mediated by mu-calpain induced much higher activation by beta gamma subunits (Banno, Y., Asano, T., and Nozawa, Y. (1994) FEBS Lett. 340, 185-188). On the basis of size and immunological cross-reactivity, mPI-PLC-1 (155 kDa) was PLC-beta 3, and mPI-PLC-2 (100 kDa) was its truncated form. The cPI-PLC (140 kDa) was recognized by the antibody selective for internal sequences of PLC-beta 3 but not by the antibody raised against its carboxyl terminus, indicating that it may be related to PLC-beta 3. Treatment of human platelets with A23187 and dibucaine, activators of calpain, caused cleavage of actin-binding protein and talin in a time-dependent manner. At the same time, decrease of PLC-beta 3 (155 and 140 kDa) and concomitant increase of the 100-kDa product of cleavage were observed on immunoblots with the antibody to internal sequences of PLC-beta 3. Furthermore, stimulation of platelets by natural agonists, thrombin and collagen, caused the cleavage of PLC-beta 3 (155 and 140 kDa) and an increase of 100 kDa PLC-beta 3 in a time- and dose-dependent manner. The cleavage of these PLC-beta 3 enzymes was completely blocked by calpain inhibitor, calpeptin, indicating that the PLC-beta 3 modification may be a consequence of platelet activation leading to activation of calpain. This is the first demonstration that PLC-beta 3 is indeed cleaved by calpain upon platelet activation by physiological agonists. The cleavage of PLC-beta 3 evoked by thrombin and collagen but not ADP was correlated with irreversible aggregation, suggesting that the PLC-beta 3 modification may play a role in secondary irreversible aggregation in agonist-stimulated human platelets.

UI	MeSH Term	Description	Entries
D007527	Isoenzymes	Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics.	Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
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
D010738	Type C Phospholipases	A subclass of phospholipases that hydrolyze the phosphoester bond found in the third position of GLYCEROPHOSPHOLIPIDS. Although the singular term phospholipase C specifically refers to an enzyme that catalyzes the hydrolysis of PHOSPHATIDYLCHOLINE (EC 3.1.4.3), it is commonly used in the literature to refer to broad variety of enzymes that specifically catalyze the hydrolysis of PHOSPHATIDYLINOSITOLS.	Lecithinase C,Phospholipase C,Phospholipases, Type C,Phospholipases C
D001792	Blood Platelets	Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.	Platelets,Thrombocytes,Blood Platelet,Platelet,Platelet, Blood,Platelets, Blood,Thrombocyte
D002154	Calpain	Cysteine proteinase found in many tissues. Hydrolyzes a variety of endogenous proteins including NEUROPEPTIDES; CYTOSKELETAL PROTEINS; proteins from SMOOTH MUSCLE; CARDIAC MUSCLE; liver; platelets; and erythrocytes. Two subclasses having high and low calcium sensitivity are known. Removes Z-discs and M-lines from myofibrils. Activates phosphorylase kinase and cyclic nucleotide-independent protein kinase. This enzyme was formerly listed as EC 3.4.22.4.	Calcium-Activated Neutral Protease,Calcium-Dependent Neutral Proteinase,Ca2+-Activated Protease,Calcium-Activated Neutral Proteinase,Calcium-Activated Protease,Calcium-Dependent Neutral Protease,Calpain I,Calpain II,Desminase,Ca2+ Activated Protease,Calcium Activated Neutral Protease,Calcium Activated Neutral Proteinase,Calcium Activated Protease,Calcium Dependent Neutral Protease,Calcium Dependent Neutral Proteinase,Neutral Protease, Calcium-Activated,Neutral Protease, Calcium-Dependent,Neutral Proteinase, Calcium-Activated,Neutral Proteinase, Calcium-Dependent,Protease, Ca2+-Activated,Protease, Calcium-Activated,Protease, Calcium-Activated Neutral,Protease, Calcium-Dependent Neutral,Proteinase, Calcium-Activated Neutral,Proteinase, Calcium-Dependent Neutral
D003094	Collagen	A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).	Avicon,Avitene,Collagen Felt,Collagen Fleece,Collagenfleece,Collastat,Dermodress,Microfibril Collagen Hemostat,Pangen,Zyderm,alpha-Collagen,Collagen Hemostat, Microfibril,alpha Collagen
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
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006868	Hydrolysis	The process of cleaving a chemical compound by the addition of a molecule of water.
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