Inhibitor of DNA Binding Protein 1 (ID1)

Inhibitor of DNA Binding Protein 1 is a helix-loop-helix (HLH) protein that can form heterodimers with members of the basic HLH family of transcription factors. The encoded protein has no DNA binding activity and therefore can inhibit the DNA binding and transcriptional activation ability of basic HLH proteins with which it interacts. This protein may play a role in cell growth, senescence, and differentiation. Two transcript variants encoding different isoforms have been found for this gene.

ID1-prime isoform is generated by a failure of the gene to splice its 1 intron, resulting in the replacement of the last 13 C-terminal amino acids with 7 different amino acids. A 2.2-kb sequence from the 5-prime region of ID1 was sufficient to direct transcription of a reporter gene, but it did not confer the growth-regulated expression normally seen with ID1.