KAT, located on chromosome 1q23.3, is highly conserved among mammals. The KAT gene spans a genomic region of approximately 1.6 kilobases and consists of 4 exons encoding a 115 amino acid protein with a molecular mass of about 12.5 kDa. The gene is expressed in several human tissues, including kidney, liver, skeletal muscle, heart, colon, thymus, spleen, placenta and lung. TSTD1 (previously referred to as KAT) is found in the cytoplasm, in the vicinity of the nuclear membrane. The TSTD1 protein is reportedly overexpressed in breast, colon, and lung carcinoma cell lines.