This gene encodes the CD4 membrane glycoprotein of T lymphocytes. The CD4 antigen acts as a coreceptor with the T-cell receptor on the T lymphocyte to recognize antigens displayed by an antigen presenting cell in the context of class II MHC molecules. The CD4 antigen is also a primary receptor for entry of the human immunodeficiency virus through interactions with the HIV Env gp120 subunit. This gene is expressed not only in T lymphocytes, but also in B cells, macrophages, granulocytes, as well as in various regions of the brain. The protein functions to initiate or augment the early phase of T-cell activation, and may function as an important mediator of indirect neuronal damage in infectious and immune-mediated diseases of the central nervous system. Multiple alternatively spliced transcript variants encoding different isoforms have been identified in this gene. [provided by RefSeq, May 2020] Annotation information: Note: This gene has been reviewed for its involvement in coronavirus biology, and is relevant for COVID-19 prognosis.

NM_000616.5; NM_001195014.3; NM_001195015.3; NM_001195016.3; NM_001195017.3; NM_001382705.1; NM_001382706.1; NM_001382707.1; NM_001382714.1

NP_000607.1; NP_001181943.1; NP_001181944.1; NP_001181945.1; NP_001181946.1; NP_001369634.1; NP_001369635.1; NP_001369636.1; NP_001369643.1