This domain represents the regulatory N-terminal non-catalytic region of Mitogen-activated protein kinase kinase kinase 4 (MEKK4) which contains a putative PH-domain. This N-terminal region acts as an autoinhibitory domain that must be dissociated from the catalytic domain to allow the activation of these kinases [1-3].

1: Cloning of a novel mitogen-activated protein kinase kinase kinase, MEKK4, that selectively regulates the c-Jun amino terminal kinase pathway. Gerwins P, Blank JL, Johnson GL; J Biol Chem. 1997;272:8288-8295. PMID:9079650

2: Regulation of MTK1/MEKK4 kinase activity by its N-terminal autoinhibitory domain and GADD45 binding. Mita H, Tsutsui J, Takekawa M, Witten EA, Saito H; Mol Cell Biol. 2002;22:4544-4555. PMID:12052864

3: MEKK4 is an effector of the embryonic TRAF4 for JNK activation. Abell AN, Johnson GL; J Biol Chem. 2005;280:35793-35796. PMID:16157600