Description
This assay employs a two-site sandwich ELISA to quantitate CIITA in samples. An antibody specific for CIITA has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any CIITA present is bound by the immobilized antibody. After removing any unbound substances, a biotin-conjugated antibody specific for CIITA is added to the wells. After washing, Streptavidin conjugated Horseradish Peroxidase (HRP) is added to the wells. Following a wash to remove any unbound avidin-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of CIITA bound in the initial step. The color development is stopped and the intensity of the color is measured.
Overview: CIITA mRNA can only be detected in human leukocyte antigen 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. However CIITA does not appear to directly bind to DNA. Instead CIITA functions through activation the transcription factor RFX5. Hence CIITA is classified as a transcriptional coactivator. The CIITA protein contains an acidic transcriptional activation domain, 4 LRRs and a GTP binding domain. The protein uses GTP binding to facilitate its own transport into the nucleus. 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