Aryl hydrocarbon receptor nuclear translocator-like protein 1 (ARNTL) or brain and muscle ARNT-Like 1 (BMAL1) is a protein that in humans is encoded by the ARNTL gene, also known as BMAL1, MOP3, and, less commonly, bHLHe5, BMAL, BMAL1C, JAP3, PASD3, and TIC. ARNTL encodes a transcription factor with a basic helix-loop-helix (bHLH) and two PAS domains. The human ARNTL gene has a predicted 24 exons and is located on the p15 band of the 11th chromosome.[4] The ARNTL protein is 626 amino acids long and plays a key role as one of the positive elements in the mammalian auto-regulatory transcription-translation negative feedback loop (TTFL), which is responsible for generating molecular circadian rhythms. Research has revealed that ARNTL is the only clock gene without which the circadian clock fails to function in humans. ARNTL has also been identified as a candidate gene for susceptibility to hypertension, diabetes, and obesity, and mutations in ARNTL have been linked to infertility, gluconeogenesis and lipogenesis problems, and altered sleep patterns. ARNTL, according to genome-wide profiling, is estimated to target more than 150 sites in the human genome, including all of the clock genes and genes encoding for proteins that regulate metabolism.