Definition

A macrolide isolated from Streptomyces tsukubaensis. Tacrolimus binds to the FKBP-12 protein and forms a complex with calcium-dependent proteins, thereby inhibiting calcineurin phosphatase activity and resulting in decreased cytokine production. This agent exhibits potent immunosuppressive activity in vivo and prevents the activation of T lymphocytes in response to antigenic or mitogenic stimulation. Tacrolimus possesses similar immunosuppressive properties to cyclosporine, but is more potent.