FKBP1A and ataxia telangiectasia: The mTOR protein is made up of 2549 amino acids and is organized into many domains, like NH2-terminal (N-HEAT), middle HEAT (M-HEAT), FAT domain (also called FKBP12-rapamycin-associated protein, ataxia-telangiectasia and transactivation/transformation), kinase domain with FRB (FKBP12 rapamycin-binding domain site) and a FAT carboxy-terminal domain.