mFluor(TM) Blue 585 Anti-human CD4 Antibody *SK3*

Extinction coefficient (cm^-1 M^-1): 45000 (PBS). Excitation (nm): 491. Emission (nm): 578. SK3 is an anti-human monoclonal antibody that recognizes the CD4 antigen. CD4 (alternatively called T4 or Leu3a) is a 55 kD member of the Ig superfamily located on the surface of cells such as macrophages, T cells, and granulocytes. CD4 has been associated with important biological processes such as membrane organization, specifically the fusion of the virus membrane with the host plasma membrane. Furthermore, it is involved with vital cellular pathways, such as the T cell receptor signaling pathway, enzyme-linked receptor protein signaling pathway, and cytokine-mediated signaling pathway. In some organisms, CD4 positively regulates peptidyl-tyrosine phosphorylation, which is an enhancer of transcription and DNA-templated and is a positive regulator of the ERK1 and ERK2 cascade. From a research standpoint, it is of biological interest due to its association with essential macromolecules/ligands such as MHC Class II, gp120, IL-16, and Lck. CD4 is a very popular antibody target, with over 180000 publications in the last decade. CD4 is commonly used in flow cytometry applications as a phenotypic marker for differentiating cell types, especially in the study of immunology. This antibody was purified through affinity chromatography and conjugated to mFluor(TM) Blue 585 (ex/em = 491/578 nm). It is compatible with the 488 nm laser and 586/15 nm bandpass filter (for example, as in the BD FACSCelesta(TM)). Protein 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. [The UniProt Consortium]