The initiator element (Inr), sometimes referred to as initiator motif, is a core promoter that is similar in function to the Pribnow box (in prokaryotes) or the TATA box (in eukaryotes). The Inr is the simplest functional promoter that is able to direct transcription initiation without a functional TATA box. It has the consensus sequence YYANWYY in humans. Similarly to the TATA box, the Inr element facilitates the binding of transcription Factor II D (TFIID). The Inr works by enhancing binding affinity and strengthening the promoter.