LIPOPROTEIN RECEPTOR C-K - DEPENDENT SIGNALING IN HUMAN PLATELETS

The study addressed to understand whether or not lipoproteins at low c oncentrations could modulate Receptor-'C' dependent platelet signallin g revealed that LDL, like exogneous cholesterol, had the capacity to i nitiate PLD-dependent platelet signalling in a dose dependent fashion and this effect was inhibited in presence of HDL; cAMP; DTT; Zn++ and butanol whereas cGMP had no effect upon this PLD-dependent signalling. Further Receptor 'C' from platelet in the purified-form displayed LDL -or cholesterol-dependent autophosphorylation at the tyrosine residues and this Receptor-'C' tyrosine kinase (Receptor-C-k) activity contrib uted to the observed LDL-or cholesterol -dependent PLD activity in hum an platelets. Based upon these results coupled with earlier results, a n attempt was made to define the lipoprotein-dependent platelet signal ling pathway.