The CD4 antigen is involved in the recognition of the type II MHC antigen. It is also a receptor for HIV. It is present on most T helper cells and normal thymocytes. The cytoplasmic portion of CD4 is associated with p56lck tyrosine kinase. CD4 expression is commonly found in human lymph nodes and tonsils. CD44 is a type 1 transmembrane glycoprotein also known as Phagocytic Glycoprotein-1 (pgp-1) and HCAM. CD44 is the receptor for hyaluronate and exists as a large number of different isoforms due to alternative RNA splicing. The major isoform expressed on lymphocytes, myeloid cells, and erythrocytes is a glycosylated type 1 transmembrane protein. Other isoforms contain glycosaminoglycans and are expressed on hematopoietic and non-hematopoietic cells. CD44 is involved in adhesion of leukocytes to endothelial cells, stromal cells, and the extracellular matrix. CD25: IL2 receptor alpha (IL2RA) and beta (IL2RB) chains, together with the common gamma chain (IL2RG), constitute the high-affinity IL2 receptor. Homodimeric alpha chains (IL2RA) result in low-affinity receptor, while homodimeric beta (IL2RB) chains produce a medium-affinity receptor. Normally an integral-membrane protein, soluble IL2RA has been isolated and determined to result from extracellular proteolyisis. Alternately-spliced IL2RA mRNAs have been isolated, but the significance of each is presently unknown. Mutations in this gene are associated with interleukin 2 receptor alpha deficiency.
CD25; CD4; CD4 antigen (p55); CD4 antigen p55; CD4 receptor; IL 2 RA; IL 2 receptor; IL 2R; IL 2R subunit alpha; IL-2 receptor subunit alpha; IL-2R alpha; IL-2R subunit alpha; IL2 RA; IL2 RA antibody; IL2 receptor; IL2 receptor subunit alpha; IL2R subunit alpha; Il2ra antibody; interleukin 2 receptor, alpha; Interleukin-2 receptor subunit alpha; Interleukin2 receptor subunit alpha; p55; sIL 2R; soluble IL 2 receptor; T-cell surface antigen T4/Leu-3; T-cell surface glycoprotein CD4; TAC antigen