Protein serotonylation is time- and concentration-dependent in aortic homogenates and can be competed against by excess 5-HT.

<p>A. Time course of protein modification for 5-HT-biotin and BAP as substrates. Representative of N = 3 separate experiments. B. Concentration-response curve for aortic protein serotonylation. Representative of N = 5 separate experiments. C. Left: Ability of weight/weight excess of 5-HT to compete off 5-HT-biotin (12. 7 µM) in a TG reaction. Lower blot demonstrates that protein was loaded equally into all lanes as observed through equal α-actin expression. Right panel shows densitometry for the band at 40–42 kDa protein. Representative of N = 6 separate experiments.