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. Author manuscript; available in PMC: 2012 Dec 17.
Published in final edited form as: Sci Signal. 2008 Oct 14;1(41):ra8. doi: 10.1126/scisignal.1162329

Fig. 4.

Fig. 4

The VILIP1 binding segment on P2X2 receptors is exposed during channel opening. (A) The cartoon shows a P2X2 receptor subunit with the location of the sites where 4C tags were inserted. The expanded blow out shows how a FlAsH fluorophore is held in place by the 4C tag. (B) Fluorescence intensity of the FlAsH-labeled constructs shown in (A), compared to that of wt P2X2. We observed meaningful FlAsH staining only in constructs carrying 4C tags. The lower graph shows that 4C-tagged and -labeled P2X2 constructs display ATP EC50 values similar to those of wt P2X2 (P > 0.05) (C) Superimposed ATP-evoked currents (upper left) and FlAsH fluorescence (middle), before during, and after ATP exposure for the indicated constructs. Only the P2X2-4C-K374 construct showed optical signals in response to ATP. The blow out shows the rising phase of the optical signal; a significant change was detected within 2 s of applying ATP.