Biomaterial Database

Quantitative assessment of polymerized and depolymerized platelet microtubules. Changes caused by aggregating agents. 1979

M Steiner, and Y Ikeda

The equilibrium between assembled and disassembled microtubules was studied in human platelets exposed to aggregating agents. Soluble and insoluble tubulin were "frozen" by addition of a glycerol-dimethyl sulfoxide-containing medium. The two pools were estimated by measuring the colchicine binding activities of total and polymerized tubulin. Resting platelets were found to contain an average of 56.2 mug tubulin/1 x 10(9) cells of which 56.7% was in polymerized form. Platelet aggregation induced by thrombin, ADP, epinephrine, or collagen produced a transient decrease in the pool of polymerized tubulin which was evident within 15 s after addition of the aggregating agent. A return to base-line values occurred within 1-4 min depending upon the specific aggregating agent used. Neither secretory release nor aggregation of platelets were found to be prerequisites for the temporary disturbance of the equilibrium between soluble and polymerized tubulin. With thrombin as the aggregating agent a clear threshold concentration could be demonstrated above with a dose-dependent dissociation response of microtubules was evident. We conclude that microtubules exist in a dynamic equilibrium between polymerized and depolymerized forms in human platelets, which is transiently disturbed by their interaction with aggregating agents.

UI	MeSH Term	Description	Entries
D010974	Platelet Aggregation	The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS.	Aggregation, Platelet
D011108	Polymers	Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).	Polymer
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
D006023	Glycoproteins	Conjugated protein-carbohydrate compounds including MUCINS; mucoid, and AMYLOID glycoproteins.	C-Glycosylated Proteins,Glycosylated Protein,Glycosylated Proteins,N-Glycosylated Proteins,O-Glycosylated Proteins,Glycoprotein,Neoglycoproteins,Protein, Glycosylated,Proteins, C-Glycosylated,Proteins, Glycosylated,Proteins, N-Glycosylated,Proteins, O-Glycosylated
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D014404	Tubulin	A microtubule subunit protein found in large quantities in mammalian brain. It has also been isolated from SPERM FLAGELLUM; CILIA; and other sources. Structurally, the protein is a dimer with a molecular weight of approximately 120,000 and a sedimentation coefficient of 5.8S. It binds to COLCHICINE; VINCRISTINE; and VINBLASTINE.	alpha-Tubulin,beta-Tubulin,delta-Tubulin,epsilon-Tubulin,gamma-Tubulin,alpha Tubulin,beta Tubulin,delta Tubulin,epsilon Tubulin,gamma Tubulin
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In