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Human CD4 / LEU3 (aa 1-208) HEK293 Cell Lysate (WB positive control)

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Human CD4 Transfected / Overexpression Cell Lysate Product Information
Expressed Host:Human Cells
Product Description:Human Cell lysate that Human CD4 / LEU3 (aa 1-208) transfected / overexpressed for Western blot (WB) positive control. The whole cell lysate is provided in 1X Sample Buffer (1X modified RIPA buffer+1X SDS loading buffer).
Sequence information: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.
Predicted N Terminal:Lys 26
Molecule Mass: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.
Human CD4 Transfected / Overexpression Cell Lysate Usage Guide
Preparation Method:Cell lysate was prepared by homogenization in ice-cold modified RIPA Lysis Buffer with cocktail of protease inhibitors (Sigma). Cell debris was removed by centrifugation. Protein concentration was determined by Bradford assay (Bio-Rad protein assay, Microplate Standard assay). The cell lysate was boiled for 5 min in 1 x SDS loading buffer (50 mM Tris-HCl pH 6.8, 12.5% glycerol, 1% sodium dodecylsulfate, 0.01% bromophenol blue) containing 5% b-mercaptoethanol, and lyophilized.
Lysis Buffer:Modified RIPA Lysis Buffer: 50 mM Tris-HCl pH 7.4, 150 mM NaCl, 1mM EDTA, 1% Triton X-100, 0.1% SDS, 1% Sodium deoxycholate, 1mM PMSF.
Quality Control Testing:12.5% SDS-PAGE Stained with Coomassie Blue after protein purification.
Stability:Samples are stable for up to twelve months from date of receipt.
Recommend Usage:1.  Centrifuge the tube for a few seconds and ensure the pellet at the bottom of the tube. 2.  Re-dissolve the pellet using 200μL pure water and boil for 2-5 min. 3. Store the lyophilized cell lysate at 4℃. After re-dissolution, recommend to aliquot it into smaller quantities and store at -80℃.
Storage Buffer:1 X Sample Buffer (1 X modified RIPA buffer+1 X SDS loading buffer).
Storage Instruction:Store at 4℃. After re-dissolution, aliquot and store at -80℃.
Application notes:Western blot (WB): Use at an assay dependent dilution.
Other Applications: Not tested.
Optimal dilutions/concentrations should be determined by the end user.
CD4 Background

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.

Human CD4 References
  • Farrar WL, et al. (1988) Characterization of CD4 glycoprotein determinant-HIV envelope protein interactions: perspectives for analog and vaccine development. Crit Rev Immunol. 8(4): 315-39.
  • Biddison WE, et al. (1989) CD4 expression and function in HLA class II-specific T cells. Immunol Rev. 109: 5-15.
  • Singh SK, et al. (2012) Mapping the interaction between the cytoplasmic domains of HIV-1 viral protein U and human CD4 with NMR spectroscopy. FEBS J. 279(19):3705-14.
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    Catalog: 10400-H08H1L-300
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