The Human Initiator Is a Distinct and Abundant Element That Is Precisely Positioned in Focused Core Promoters. Homo sapiens

DNA sequence signals in the core promoter, such as the initiator (Inr), direct the initiation of transcription by RNA polymerase II. Here we show that the human Inr has the consensus of BBCA+1BW at focused promoters, and that sequences from −1 to +3 are most important for transcriptional activity. The analysis of 7,678 focused transcription start sites revealed 40% with a perfect match to the Inr and 16% with a single mismatch outside of the CA+1 core. TATA-like sequences are underrepresented in Inr promoters. This Inr consensus should serve as a useful beacon for the study of transcription in humans.