The genes that are deficient in TATA-BOX are primarily housekeeping proteins and a few developmental regulatory genes. The former regulates basic biochemical pathways, including genes necessary for nucleotide synthesis. The latter include active immune system development genes and homeotic developmental genes. TATA-BOX is typically present in specialized genes (luxury genes), such as hemoglobin and keratin. TBP, a member of the TFIID transcription factor, is the binding protein of TATA-BOX. When transcription factor II and RNA polymerase II bind to the promoter, they form the superinitiation complex, with TATA-BOX serving as a critical component. The Homeobox, MADS-box, and HMG box in the enhancer, along with the TATA-BOX in the promoter, significantly influence the efficient transcription efficiency of RNA polymerase II. The primary function of RNA polymerase II is to transcribe hnRNA (precursor of mRNA), snRNA, and miRNA.