CD4 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. (Microbial infection) Primary receptor for human immunodeficiency virus-1 (HIV-1). Down-regulated by HIV-1 Vpu. Acts as a receptor for Human Herpes virus 7/HHV-7. 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. Note: This description may include information from UniProtKB.
Protein type: Cell surface; Membrane protein, integral
Chromosomal Location of mouse Ortholog: 6 F2|6 59.17 cM
Cellular Component:  cell surface; endoplasmic reticulum lumen; endoplasmic reticulum membrane; external side of plasma membrane; integral component of membrane; integral component of plasma membrane; membrane; membrane raft; plasma membrane
Molecular Function:  coreceptor activity; enzyme binding; identical protein binding; immunoglobulin binding; interleukin-16 binding; interleukin-16 receptor activity; MHC class II protein binding; protein binding; protein homodimerization activity; protein kinase binding; protein tyrosine kinase binding; signaling receptor binding; zinc ion binding
Biological Process:  adaptive immune response; cell adhesion; cell surface receptor signaling pathway; cellular response to granulocyte macrophage colony-stimulating factor stimulus; cytokine production; defense response to Gram-negative bacterium; helper T cell enhancement of adaptive immune response; immune response; immune system process; induction by virus of host cell-cell fusion; interleukin-15-mediated signaling pathway; macrophage differentiation; maintenance of protein location in cell; positive regulation of calcium ion transport into cytosol; positive regulation of calcium-mediated signaling; positive regulation of ERK1 and ERK2 cascade; positive regulation of I-kappaB kinase/NF-kappaB signaling; positive regulation of kinase activity; positive regulation of MAPK cascade; positive regulation of monocyte differentiation; positive regulation of peptidyl-tyrosine phosphorylation; positive regulation of protein kinase activity; positive regulation of protein phosphorylation; positive regulation of T cell activation; positive regulation of T cell proliferation; positive regulation of transcription, DNA-templated; positive regulation of viral entry into host cell; regulation of calcium ion transport; regulation of T cell activation; T cell activation; T cell differentiation; T cell selection
Reference #:  P06332 (UniProtKB)
Alt. Names/Synonyms: Cd4; CD4 antigen; L3T; L3T4; Ly-; Ly-4; OTTMUSP00000027399; T-cell differentiation antigen L3T4; T-cell surface antigen T4/Leu-3; T-cell surface glycoprotein CD4; T-cell surface glycoprotein CD4 precursor (T-cell surface antigen T4/Leu-3) (T-cell differentiation antigen L3T4)
Gene Symbols: Cd4
Molecular weight: 51,297 Da
Basal Isoelectric point: 9.31  Predict pI for various phosphorylation states
CST Pathways:  T Cell Receptor Signaling
Protein-Specific Antibodies, siRNAs or Recombinant Proteins from Cell Signaling Technology® Total Proteins
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Protein Structure Not Found.

Cross-references to other databases:  AlphaFold  |  STRING  |  Reactome  |  BioGPS  |  Pfam  |  Phospho.ELM  |  NetworKIN  |  UniProtKB  |  Entrez-Gene  |  Ensembl Gene