Evidence has been presented for the existence in rat liver of P2-purinoceptors which are involved in the control of glycogenolysis. Isolated rat hepatocytes and purified liver plasma membranes have been used to study the binding of the ATP analogue adenosine 5′-[alpha- [35S]thio]triphosphate (ATP alpha [35S]) to these postulated P2-purinoceptors. The nucleotide analogue behaves as a full agonist for the activation of glycogen phosphorylase in isolated hepatocytes, 0.3 microM being required for half-maximal activation. Specific binding of ATP alpha [35S] to hepatocytes and plasma membranes occurs within 1 min and is essentially reversible. The analysis of the dose-dependency at equilibrium indicates the presence of binding sites with Kd of 0.23 microM with hepatocytes and Kd of 0.11 microM with plasma membranes. The relative affinities of 10 nucleotide analogues were deduced from competition experiments for ATP alpha [35S] binding to hepatocytes, and these correlated highly with their biological activity (activation of glycogen phosphorylase in hepatocytes). For all the agonists, binding occurs in the same concentration range as the biological effect. These data clearly suggest that the detected binding sites correspond to the physiological P2-purinoceptors involved in the regulation of liver glycogenolysis. The rank order of potency of some ATP analogues suggests that liver possesses the P2Y-subclass of P2-purinoceptors.
Skip Nav Destination
Article navigation
December 1986
- Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
- PDF Icon PDF LinkAdvertising
Research Article|
December 01 1986
Characterization of the liver P2-purinoceptor involved in the activation of glycogen phosphorylase
Biochem J (1986) 240 (2): 367–371.
Citation
S Keppens, H De Wulf; Characterization of the liver P2-purinoceptor involved in the activation of glycogen phosphorylase. Biochem J 1 December 1986; 240 (2): 367–371. doi: https://doi.org/10.1042/bj2400367
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Biochemical Society Member Sign in
Sign InSign in via your Institution
Sign in via your InstitutionGet Access To This Article
Cited By
Related Articles
Agonists for endothelial P 2 purinoceptors trigger a signalling pathway producing Ca 2+ responses in lymphocytes adherent to endothelial cells
Biochem J (October,1995)
Evidence for P2-purinoceptor-mediated uptake of Ca2+ across a fish (Oreochromis mossambicus) intestinal brush border membrane
Biochem J (February,1997)