CD4 [MEM-16]

MEM-16

HPB cell line (human peripheral blood leukemia T-cells)

CD4

Purified from ascites by precipitation methods and size-exclusion chromatography.  Storage

FACS: Recommended

Peripheral blood lymphocytes CD4 is a single chain transmembrane glycoprotein and belongs to immunoglobulin supergene family. In extracellular region there are 4 immunoglobulin-like domains (1 Ig-like V-type and 3 Ig-like C2-type). Transmembrane region forms 25 aa cytoplasmic tail consists of 38 aa. Domains 1 2 and 4 are stabilized by disulfide bonds. The intracellular domain of CD4 is associated with p56Lck a Src-like protein tyrosine kinase. It was described that CD4 segregates into specific detergent-resistant T-cell membrane microdomains.  Extracellular ligands: MHC class II molecules (binds to CDR2-like region in CD4 domain 1); HIV envelope protein gp120 (binds to CDR2-like region in CD4 domain 1); IL-16 (binds to CD4 domain 3) Human seminal plasma glycoprotein gp17 (binds to CD4 domain 1) L-selectin Intracellular ligands: p56LckCD4 is a co-receptor involved in immune response (co-receptor activity in binding to MHC class II molecules) and HIV infection (human immunodeficiency virus; CD4 is primary receptor for HIV-1 surface glycoprotein gp120). CD4 regulates T-cell activation T/B-cell adhesion T-cell diferentiation T-cell selection and signal transduction. Defects in antigen presentation (MHC class II) cause dysfunction of CD4+ T-cells and their almost complete absence in patients blood tissue and organs (SCID immunodeficiency).

Associates with LCK. Binds to HIV-1 gp120 and to P4HB/PDI and upon HIV-1 binding to the cell membrane is part of P4HB/PDI-CD4-CXCR4-gp120 complex. Interacts with HIV-1 Envelope polyprotein gp160 and protein Vpu. Interacts with Human Herpes virus 7 capsid proteins.

Palmitoylation and association with LCK contribute to the enrichment of CD4 in lipid rafts.

Contains 3 Ig-like C2-type (immunoglobulin-like) domains.