Apoptosis Signal Regulating Kinase 1 (ASK1)

Apoptosis signal-regulating kinase 1 is an enzyme which in humans is encoded by the MAP3K5 gene. This gene is located on chromosome 6 at locus 6q22.33 and the transcribed protein contains 1,374 amino acids with 11 kinase subdomains. The ASK1 (MAPKKK5) protein phosphorylates and activates MKK4 (aliases SERK1, MAPKK4) in vitro, and activates c-Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK) during transient expression in COS and 293 cells; ASK1 does not activate MAPK/ERK.ASK1 found in the inactive form, bound to reduced thioredoxin.

When oxidized by a reactive oxygen species, Trx dissociates from ASK1. The ASK1, which is found as a homo-oligodimer, autophosphorylates and becomes an active MAP kinase kinase kinase.