Below is the abstract of a recent review article describing the importance of M1 (Linear) polyubiquitination. The article is, “Linear Polyubiquitination: A Crucial Regulator of NF-κB Activation” by Dr. Kazuhiro Iwai.
“NF-κB is a transcription factor known to be involved in pleomorphic biological phenomena such as inflammation and immune responses. Abnormal activation of NF-κB has been reported in many pathological conditions, including malignant tumors. Therefore, the NF-κB activation pathway has been extensively studied and involvement of the ubiquitin conjugation system in the NF-κB activation pathways has been revealed. Although the ubiquitin conjugation system was discovered as a part of a protein degradation pathway, non-degradable roles of the ubiquitin system have been revealed recently. Several types of polyubiquitin chains exist in cells and the type of chain seems to determine how ubiquitinated proteins are regulated. We have identified that a new type of polyubiquitin chain, the linear polyubiquitin chain, plays a crucial role in regulating the NF-κB activation pathway in non-degradable manner. In this chapter, the discovery, roles in NF-κB activation, and involvement in the pathogenesis of cancers of linear ubiquitination will be discussed.”