cd06613: STKc_MAP4K3_like (this model, PSSM-Id:173727 is obsolete and has been replaced by 270788)
Catalytic domain of Mitogen-activated protein kinase kinase kinase kinase-like Protein Serine/Threonine Kinases
Serine/threonine kinases (STKs), mitogen-activated protein kinase (MAPK) kinase kinase kinase 3 (MAPKKKK3 or MAP4K3)-like subfamily, catalytic (c) domain. STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The MAP4K3-like subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. This subfamily includes MAP4K3, MAP4K1, MAP4K2, MAP4K5, and related proteins. Vertebrate members contain an N-terminal catalytic domain and a C-terminal citron homology (CNH) regulatory domain, similar to MAP4K4/6. MAP4Ks are involved in some MAPK signaling pathways that are important in mediating cellular responses to extracellular signals by activating a MAPK kinase kinase (MAPKKK or MAP3K or MKKK). Each MAPK cascade is activated either by a small GTP-binding protein or by an adaptor protein, which transmits the signal either directly to a MAP3K to start the triple kinase core cascade or indirectly through a mediator kinase, a MAP4K. MAP4K1, also called haematopoietic progenitor kinase 1 (HPK1), is a hematopoietic-specific STK involved in many cellular signaling cascades including MAPK, antigen receptor, apoptosis, growth factor, and cytokine signaling. It participates in the regulation of T cell receptor signaling and T cell-mediated immune responses. MAP4K2 was referred to as germinal center (GC) kinase because of its preferred location in GC B cells. MAP4K3 plays a role in the nutrient-responsive pathway of mTOR (mammalian target of rapamycin) signaling. It is required in the activation of S6 kinase by amino acids and for the phosphorylation of the mTOR-regulated inhibitor of eukaryotic initiation factor 4E. MAP4K5, also called germinal center kinase-related enzyme (GCKR), has been shown to activate the MAPK c-Jun N-terminal kinase (JNK).