Human CD4 (aa 1-208, His Tag) recombinant protein
T-cell surface glycoprotein CD4, is a single-pass type I membrane protein. CD4 contains three Ig-like C2-type (immunoglobulin-like) domains and one Ig-like V-type (immunoglobulin-like) domain. CD4 is a glycoprotein expressed on the surface of T helper cells, regulatory T cells, monocytes, macrophages, and dendritic cells. The CD4 surface determinant, previously associated as a phenotypic marker for helper/inducer subsets of T lymphocytes, has now been critically identified as the binding/entry protein for human immunodeficiency viruses (HIV). The human CD4 molecule is readily detectable on monocytes, T lymphocytes, and brain tissues. All human tissue sources of CD4 bind radiolabeled gp120 to the same relative degree; however, the murine homologous protein, L3T4, does not bind the HIV envelope protein. CD4 is a co-receptor that assists the T cell receptor (TCR) to activate its T cell following an interaction with an antigen presenting cell. Using its portion that resides inside the T cell, CD4 amplifies the signal generated by the TCR. CD4 interacts directly with MHC class II molecules on the surface of the antigen presenting cell via its extracellular domain. The CD4 molecule is currently the object of intense interest and investigation both because of its role in normal T-cell function, and because of its role in HIV infection. CD4 is a primary receptor used by HIV-1 to gain entry into host T cells. HIV infection leads to a progressive reduction of the number of T cells possessing CD4 receptors. Viral protein U (VpU) of HIV-1 plays an important role in downregulation of the main HIV-1 receptor CD4 from the surface of infected cells. Physical binding of VpU to newly synthesized CD4 in the endoplasmic reticulum is an early step in a pathway leading to proteasomal degradation of CD4. Amino acids in both helices found in the cytoplasmic region of VpU in membrane-mimicking detergent micelles experience chemical shift perturbations upon binding to CD4, whereas amino acids between the two helices and at the C-terminus of VpU show no or only small changes, respectively. Paramagnetic spin labels were attached at three sequence positions of a CD4 peptide comprising the transmembrane and cytosolic domains of the receptor. VpU binds to a membrane-proximal region in the cytoplasmic domain of CD4.
cDNA FLJ50658, highly similar to T-cell surface glycoprotein CD4
Protein short names
CD4; L3T4; CD4MUT; LY-4
A DNA sequence encoding the human CD4 (NP_000607.1) N-terminal two domains (D1D2) (Met 1-Ser 208) was fused with a polyhistidine tag at the C-terminus.
The secreted recombinant human CD4 (aa 1-208) consists of 194 amino acids and has a predicted molecular mass of 21.7 kDa. In SDS-PAGE under reducing conditions, the apparent molecular mass of rhCD4 is approximately 26 kDa.
> 94 % as determined by SDS-PAGE
1. Measured by its ability to bind human CD28 in a functional ELISA.
2. Measured by the ability of the immobilized protein to support the adhesion of HeLa human cervical epithelial carcinoma cells. When 5 x 10E4 cells/well are added to CD4 coated plates (2.5 μg/ml and 100 μl/well), approximately 40 %-60 % will adhere specifically after 60 minutes at 37℃.
Human CD4 / LEU3 Protein (aa 1-208, His Tag) SDS-PAGE
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