Proteins (inhibitor of DNA-binding proteins) that regulate tissue-specific transcription by binding to basic helix–loop–helix (bHLH) transcription factors to form a nonfunctional heterodimer. They themselves contain a helix–loop–helix motif through which they interact with the bHLH domain of the transcription factor. They play a part in cell growth, senescence, differentiation, and angiogenesis. For example, ID1 and ID2 are expressed at high levels in pro-B-cells and are down-regulated as cells differentiate into pre-B and mature B cells; ID4 inhibits the transactivation of the muscle creatine kinase E-box enhancer by MyoD and may be a tumour suppressor.
Subjects: Medicine and Health.