Tags: Protein.
CTLA-4 (Cytotoxic T-Lymphocyte Antigen 4) also known as CD152 (Cluster of differentiation 152) is a protein receptor that downregulates the immune system. CTLA4 is found on the surface of T cells which lead the cellular immune attack on antigens. The T cell attack can be turned on by stimulating the CD28 receptor on the T cell. The T cell attack can be turned off by stimulating the CTLA4 receptor which acts as an off switch.In humans the CTLA4 protein is encoded by the CTLA4 gene.