A TATA box is an upstream regulatory region, formed of repeating T and A nucleotides. This non-coding region is important in regulating gene transcription, being the transcription start site. This allows the targeting of RNA polymerase to the transcription start site of genes, enabling protein expression (as the RNA polymerase is able to recognise the TATA repeat sequence to initiate binding).
Mutations in the TATA box region can lead to issues expressing proteins, as occurs in Huntington’s disease.