Mouse CD4 Antibody

CD4 (Cluster of Differentiation #4; also L3T4) is a 55 kDa member of the Ig Superfamily of molecules.  It is expressed on a variety of hematopoietic cell types, including immature thymocytes, a number of variable phenotype single positive T cells (i.e.- CD25+; CD39+; Th1, 2 and 17 type cells), stimulated CD8+ T cells, pluripotent bone marrow stem cells, and NKT cells.  Although CD4 is a standard phenotype marker, functionally, the molecule is known to bind to APC MHC class II, and to associate with adjacent CD3 molecules to link p56^lck with the lymphocyte TCR:CD3 complex.  Mature mouse CD4 is a 431 amino acid (aa) type I transmembrane glycoprotein.  It contains a 368 aa extracellular region (aa 27-394) plus a 40 aa cytoplasmic domain (aa 418-457).  The extracellular region contains one V-type (aa 27-128) and three C2-type Ig-like domains (aa 129-374).  There is one alternative start site at Met241 that is utilized in brain.  Over aa 27-394, mouse CD4 shares 53% and 72% aa identity with human and rat CD4, respectively.