ID1: Proteins and Enzymes

ID1 is a negative regulator of helix-loop-helix (HLH) DNA binding proteins. ID1 contains a HLH motif but no DNA binding motif, therefore, upon binding other HLH proteins, ID1 acts a dominant negative regulator. ID1 can be found in both cytoplasmic and nuclear cell fractions. Increased ID1 expression is associated with cellular proliferation and cancer.