CD4 Protein, Rat (HEK293, His)

CD4, an integral membrane glycoprotein, plays a crucial role in orchestrating immune responses against external and internal threats. Primarily functioning as a coreceptor for MHC class II molecule:peptide complexes in T-cells, CD4 facilitates the recognition of antigens derived from extracellular proteins. Interacting simultaneously with the T-cell receptor (TCR) and MHC class II on antigen-presenting cells (APCs), CD4 recruits the Src kinase LCK to the TCR-CD3 complex, initiating intracellular signaling pathways that culminate in lymphokine production, cellular motility, adhesion, and activation of T-helper cells. Beyond T-cells, CD4 contributes to differentiation, activation, cytokine expression, and cell migration in macrophages or NK cells through a TCR/LCK-independent pathway. It also plays a role in the thymic development of T-helper cells and triggers the differentiation of monocytes into functional mature macrophages. The protein forms disulfide-linked homodimers on the cell surface and interacts with LCK, PTK2/FAK1, P4HB/PDI, and IL16. Additionally, CD4 binds to MHCII alpha and beta chains, enhancing the affinity of TCR for peptide-MHCII and facilitating adhesion between T cells and APCs through CD4 oligomerization.