ubiquitin-like (Ubl) domain found in inhibitor of nuclear factor kappa-B kinases, IKK-alpha and IKK-beta, and similar proteins
IKK, also termed IkappaB kinase, is an enzyme complex involved in propagating the cellular response to inflammation. It is part of the upstream nuclear factor kappa-B kinase (NF-kappaB) signal transduction cascade, and plays an important role in regulating the NF-kappaB transcription factor. IKK is composed of three subunits, IKK-alpha/CHUK, IKK-beta/IKBKB, and IKK-gamma/NEMO. The IKK-alpha and IKK-beta subunits together are catalytically active whereas the IKK-gamma subunit serves a regulatory function. IKK-alpha and IKK-beta phosphorylate the IkappaB proteins, marking them for degradation via ubiquitination and allowing NF-kappaB transcription factors to go into the nucleus. IKK-alpha, also known as IKK-A, or IkappaB kinase A (IkBKA), or conserved helix-loop-helix ubiquitous kinase (CHUK), or I-kappa-B kinase 1 (IKK1), or nuclear factor NF-kappa-B inhibitor kinase alpha (NFKBIKA), or transcription factor 16 (TCF-16), belongs to the serine/threonine protein kinase family. In addition to NF-kappaB response, it has many additional cellular targets in an NF-kappaB-independent manner. For instance, it plays a role in epidermal differentiation, as well as in the regulation of the cell cycle protein cyclin D1. IKK-beta, also known as IKK-B, or IkappaB kinase B (IkBKB), or I-kappa-B kinase 2 (IKK2), or nuclear factor NF-kappa-B inhibitor kinase beta (NFKBIKB), belongs to the serine/threonine protein kinase family as well. It interacts with many different protein partners and has been implicated in the treatment of many inflammatory diseases and cancers. Both IKK-alpha and IKK-beta contain an N-terminal catalytic domain followed by a conserved ubiquitin-like (Ubl) domain with a beta-grasp Ubl fold, a common structure involved in protein-protein interactions.
Feature 1: key conserved lysine K27, 1 residue position
Conserved feature residue pattern:[KR]
Comment:K27 (Ub numbering) is a lysine conserved in the Ubl_ubiquitin_like family; it is one of 7 lysines involved in chain linkage in ubiquitin (K6, K11, K27, K29, K33, K48, or K63, Ub numbering), and it is poorly conserved in this family, the other 6 lysines are not conserved in this family, for most the residue corresponding to K63 is a conserved Glu/Asp; may have other functions, for example in NEDD8 K27 is involved in the mechanism of protein neddylation