Fig. 1. Expression of the PAF receptor in erythrocytes. (A) Ponceau-Red protein-staining of a western blot of protein extracts from whole blood, diluted whole blood (1:20), purified erythrocytes (RBCs) or diluted platelets (1:20). Fifty microgramms or 2.5 µg (1:20) of protein were loaded per lane. The purified erythrocyte preparation contained 2.9% platelets and 4.7% white blood cells of the original whole blood sample. The molecular mass marker (size marker) is shown in the middle of the blot. (B) Erythrocyte protein extracts were prepared as described in A. Expression of the PAF receptor was then analysed by western blot with a polyclonal goat anti-PAF-receptor antibody in the presence (left) or absence (right) of specific blocking peptide. Positions of molecular mass markers are indicated in the middle. The arrow indicates the position of the PAF receptor. The asterisk indicates a non-specific band in whole blood extracts. (C) Erythrocyte protein extracts from the blood of four different donors (# 1-4) were prepared and 50 µg of protein were loaded per lane. Expression of the PAF receptor was then analysed by western blot with a polyclonal goat anti-PAF-receptor antibody (left blot). Additionally, 50 µg of the same erythrocyte extracts were loaded per lane and a platelet extract was included as positive control (Platelets). Expression of the platelet marker CD61 was analysed by western blot with a monoclonal mouse anti-CD61 antibody (right blot). Positions of molecular mass markers are indicated at the left of each blot. The arrows indicate the positions of PAF receptor (left blot) and CD61 (right blot). Representative immunoblots of three independent experiments are shown.