CIITA mRNA can only be detected in human leukocyte antigen (HLA) system class II-positive cell lines and tissues. This highly restricted tissue distribution suggests that expression of HLA class II genes is to a large extent under the control of CIITA.[3] However CIITA does not appear to directly bind to DNA.[3] Instead CIITA functions through activation of the transcription factorRFX5.[4] Hence CIITA is classified as a transcriptional coactivator.
The CIITA protein contains an acidic transcriptional activation domain, 4 LRRs (leucine-rich repeats) and a GTP binding domain.[5] The protein uses GTP binding to facilitate its own transport into the nucleus.[6] Once in the nucleus, the protein acts as a positive regulator of class II major histocompatibility complex gene transcription, and is often referred to as the "master control factor" for the expression of these genes.[7][8]
↑ 1.01.1Steimle V, Otten LA, Zufferey M, Mach B (Oct 1993). "Complementation cloning of an MHC class II transactivator mutated in hereditary MHC class II deficiency (or bare lymphocyte syndrome)". Cell. 75 (1): 135–46. doi:10.1016/S0092-8674(05)80090-X. PMID8402893.
↑LeibundGut-Landmann S, Waldburger JM, Krawczyk M, Otten LA, Suter T, Fontana A, Acha-Orbea H, Reith W (Jun 2004). "Mini-review: Specificity and expression of CIITA, the master regulator of MHC class II genes". European Journal of Immunology. 34 (6): 1513–25. doi:10.1002/eji.200424964. PMID15162420.
↑Raval A, Weissman JD, Howcroft TK, Singer DS (Jan 2003). "The GTP-binding domain of class II transactivator regulates its nuclear export". Journal of Immunology. 170 (2): 922–30. doi:10.4049/jimmunol.170.2.922. PMID12517958.