Gap 26 TFA is a connexin mimetic peptide, composed of residue numbers 63-75 of the first extracellular loop of connexin 43 (gap junction blocker), containing the SHVR amino acid motif[1].

Gap 26 (0.25 mg/mL, 30 min) reduces the wave size in the three cell lines (RBE4, SV-ARBEC and ECV304). Gap 26 (0.25 mg/mL, 30 min) completely abolishes the InsP3-triggered ATP response and reduced the ATP release to below the control level, indicating that the basal ATP release is also affected[1].Gap 26 does indeed significantly inhibit our InsP3-triggered intercellular calcium waves, but it did not have any effect on dye coupling through junctional channels as evidenced by the FRAP experiments, despite the fact that connexin 43 was present in the cell lines used[1].Gap 26 (100-300 μM) dose-dependently reduces the rhythmic responses of rabbit superior mesenteric arteries, with IC50 of 28.4 ± 3.4 μM[2].

[1]. Katleen Braet, et al. Photoliberating inositol-1,4,5-trisphosphate triggers ATP release that is blocked by the connexin mimetic peptide gap 26. Cell Calcium. 2003 Jan;33(1):37-48. [2]. Chaytor AT, et al. Peptides homologous to extracellular loop motifs of connexin 43 reversibly abolish rhythmic contractile activity in rabbit arteries. J Physiol. 1997 Aug 15;503 ( Pt 1):99-110.