Abundant amounts of diadenosine 5',5"'-P1,P4-tetraphosphate are present and releasable, but metabolically inactive, in human platelets

• Published in: Biochemical journal Vol. 208; no. 3; pp. 737 - 742
• Main Authors: Flodgaard, H, Klenow, H
• Format: Journal Article
• Language: English
• Published: England 15-12-1982
• Subjects: Adenine Nucleotides - blood; Adenosine Triphosphate - blood; Blood Platelets - drug effects; Blood Platelets - metabolism; Chromatography, High Pressure Liquid; Dinucleoside Phosphates; Humans; In Vitro Techniques; Phosphodiesterase I; Phosphoric Diester Hydrolases - pharmacology; Platelet Aggregation - drug effects; Ribonucleotides - blood; Thrombin - pharmacology
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2080737

Diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A) may be formed in the back reaction of the amino acid-activation reaction [Zamecnik, Stephenson, Janeway & Randerath (1966) Biochem. Biophys. Res. Commun. 24, 91-98]. On the basis of a number of observations of the properties of Ap4A it has been suggested that it may have a signal function for the initiation of DNA replication in eukaryotic cells] Grummt (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 371-375]. In the present paper human platelets have been shown to contain relatively large amounts of Ap4A. The compound is apparently metabolic inactive in platelets, but it is almost quantitatively released when platelets are activated to aggregate by treatment with thrombin. The results are discussed in connection with the known growth-stimulating activity of platelets.