PT  - JOURNAL ARTICLE
AU  - Ho-Sam Ahn
AU  - Carolyn Foster
AU  - George Boykow
AU  - Leyla Arik
AU  - April Smith-Torhan
AU  - David Hesk
AU  - Meeta Chatterjee
TI  - Binding of a Thrombin Receptor Tethered Ligand Analogue to Human Platelet Thrombin Receptor
AID  - 10.1124/mol.51.2.350
DP  - 1997 Feb 01
TA  - Molecular Pharmacology
PG  - 350--356
VI  - 51
IP  - 2
4099  - http://molpharm.aspetjournals.org/content/51/2/350.short
4100  - http://molpharm.aspetjournals.org/content/51/2/350.full
SO  - Mol Pharmacol1997 Feb 01; 51
AB  - A thrombin receptor-radioligand binding assay was developed using [3H]A(pF-F)R(ChA)(hR)Y-NH2([3H]haTRAP), a high affinity thrombin receptor-activating peptide (TRAP), and human platelet membranes. Scatchard analysis of saturation binding data indicated that [3H]haTRAP bound to platelet membranes with aK d of 15 nm and a B max of 5.2 pmol/mg of protein. The binding was reduced by GPPNHP, a nonmetabolizable GTP analogue. Various TRAPs and a TRAP antagonist, but not other receptor agonists, displaced [3H]haTRAP from the binding sites. SFLLRN-NH2, a thrombin receptor-tethered ligand analogue, and [3H]haTRAP exhibited competitive binding for the same binding sites. The relative affinity of these peptides for the binding site paralleled their EC50 or IC50 values for platelet aggregation. These data indicate that [3H]haTRAP binds specifically and saturably to the functioning G protein-linked thrombin (tethered ligand) receptor in human platelet membranes.