The lower band on the GRK5 blot represents a phosphorylated form of GRK5.

(A) Representative Western blot showing the results of the phosphatase treatment of the human striatal samples. Samples were incubated with different amounts of alkaline phosphatase (calf intestinal, Promega) for 30 min at 37°C and blotted with the rabbit anti-GRK5 antibody sc-565 (Santa Cruz Biotechnology, Santa Cruz, CA) that shows high affinity to the lower band but detects both. Control – untreated sample, and Co, 37°C – a sample incubated for 30 min at 37°C without phosphatase. Note the disappearance of the lower band upon treatment and corresponding increase in the thickness of the upper band. (B) Quantification of four independent experiments (the values obtained with the lower amount of the phosphatase). * - p<0.05 as compared to Co, 37°C according to two-tailed Student's test.