NHL repeat domain of the Drosophila brain-tumor protein (brat) and similar proteins
Drosophila brain-tumor (brat) has been identified as a tumor suppressor that negatively regulates cell proliferation during development of the Drosophila larval brain. It appears to be recruited to the 3'-untranslated region of hunchback RNA and regulates its translation by forming a complex with Pumilio (Pum) and Nanos (Nos). The NHL domain of brat appears to be involved by interacting with the RNA-binding Puf repeats of Pumilio, a sequence-specific RNA binding protein. This family also contains the Caenorhabditis elegans homolog NCL-1. The NHL (NCL-1, HT2A and LIN-41) repeat is found in multiple tandem copies, typically as 6 instances. It is about 40 residues long and resembles the WD repeat and other beta-propeller structures.