act1 (Xequel Bio)

act1 (Alpha Connexin C-Terminal peptide), also known as FSR peptide or granexin, is a synthetic 25-amino acid peptide developed by First String Research (now Xequel Bio) that mimics the carboxyl-terminal (C-terminal) sequence of Connexin 43 (Cx43). It functions as a competitive inhibitor of the interaction between Cx43 and the PDZ2 domain of the scaffolding protein Zonula Occludens-1 (ZO-1). By disrupting this interaction, act1 promotes the sequestration of Cx43 hemichannels into gap junction plaques, which reduces pro-inflammatory hemichannel signaling and enhances gap junctional intercellular communication. This dual action helps to stabilize the wound environment, reduce inflammation, and accelerate re-epithelialization. act1 is primarily being developed as a topical gel (Granexin) for the treatment of chronic wounds, such as diabetic foot ulcers and venous leg ulcers, as well as for improving the healing of surgical incisions and reducing scarring.

Brand names

Granexin

Other names

Alpha Connexin C-Terminal peptideAlpha-Connexin Carboxyl-Terminal peptideACT-1ACT1ACT 1