CD4 Rabbit Polyclonal Antibody

Function

Integral membrane glycoprotein that plays an essential role in the immune response and serves multiple functions in responses against both external and internal offenses. In T-cells, functions primarily as a coreceptor for MHC class II molecule:peptide complex. The antigens presented by class II peptides are derived from extracellular proteins while class I peptides are derived from cytosolic proteins. Interacts simultaneously with the T-cell receptor (TCR) and the MHC class II presented by antigen presenting cells (APCs). In turn, recruits the Src kinase LCK to the vicinity of the TCR-CD3 complex. LCK then initiates different intracellular signaling pathways by phosphorylating various substrates ultimately leading to lymphokine production, motility, adhesion and activation of T-helper cells. In other cells such as macrophages or NK cells, plays a role in differentiation/activation, cytokine expression and cell migration in a TCR/LCK-independent pathway. Participates in the development of T-helper cells in the thymus and triggers the differentiation of monocytes into functional mature macrophages.

Background References

1. Parnes J R et al. L3T4 and the immunoglobulin gene superfamily: new relationships between the immune system and the nervous system. Immunol Rev 100:109-127 (1987).

2. Gorman S D et al. Structure of the mouse gene encoding CD4 and an unusual transcript in brain. Proc Natl Acad Sci USA 84:7644-7648 (1987).

3. Rudd CE. CD4,CD8 and the TCR-CD3 complex: a novel class of protein-tyrosine kinase receptor. Immunol Today 11(11):400-406 (1990).

Tissue Specificity

Highly expressed in T-helper cells. The presence of CD4 is a hallmark of T-helper cells which are specialized in the activation and growth of cytotoxic T-cells, regulation of B cells, or activation of phagocytes. CD4 is also present in other immune cells such as macrophages, dendritic cells or NK cells.

Post-translational Modification

Palmitoylation and association with LCK contribute to the enrichment of CD4 in lipid rafts.; Phosphorylated by PKC; phosphorylation at Ser-433 plays an important role for CD4 internalization.

Subcellular Location

Cell Membrane.

UNIPROT

SwissProt: P01730 Human

Synonyms