Livin

By Rachel M.A. Linger, Ph.D.

Survivin is an anti-apoptotic protein which is the smallest protein within a large family of proteins including X-linked IAP, c-IAP1 and 2, IAP-like protein-2, melanoma IAP, NAIP, and Livin. Survivin is responsible for a wide range of basic cellular functions that include the cell cycle regulation, fetal development, cell migration, and tumor progression.

The survivin anti-apoptotic protein is the smallest member of a large family of proteins such as X-linked IAP, c-IAP1 and 2, IAP-like protein-2, melanoma IAP, Livin, and NAIP. Survivin regulates basic physiological events such as the cell cycle, tumor progression, fetal development, and cell migration.

Livin is a member of the inhibitor of apoptosis proteins (IAP) family that regulates programmed cell death. The Livin protein contains a single baculovirus IAP repeat (BIR) essential for function, along with a COOH-terminal RING-type zinc finger domain. In general, IAP proteins block apoptosis by binding and inhibiting caspases through this BIR domain. Two Livin splicing variants, alpha and beta, have been identified, and each has different anti-apoptotic properties. With Livin expression low in adult tissues, it is somewhat higher in developmental tissues.