P79184 · CD4_MACFU

Function

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.

GO annotations

all annotationsall molecular functionvirus receptor activitydna bindingrna bindingcytoskeletal motor activitycatalytic activitygtpase activitystructural molecule activitytransporter activitycytoskeletal protein bindinglipid bindingcyclase activityantioxidant activityoxidoreductase activitytransferase activityhydrolase activitylyase activityisomerase activityligase activityprotein tag activitycargo receptor activityhistone bindingprotein folding chaperonetranslation regulator activitynutrient reservoir activityreceptor ligand activitymolecular transducer activitymolecular adaptor activitytoxin activitycell adhesion mediator activitymolecular function regulator activityvirus coreceptor activitycatalytic activity, acting on a proteincatalytic activity, acting on dnacatalytic activity, acting on rnamolecular carrier activitytranscription regulator activitygeneral transcription initiation factor activitymolecular sensor activitymolecular sequestering activityatp-dependent activityother molecular functionall biological processmitotic cell cyclecytokinesiscytoplasmic translationimmune system processmuscle system processcirculatory system processrenal system processrespiratory system processcarbohydrate metabolic processgeneration of precursor metabolites and energydna replicationdna repairdna recombinationchromatin organizationdna-templated transcriptionregulation of dna-templated transcriptiontrna metabolic processprotein foldingprotein glycosylationamino acid metabolic processmodified amino acid metabolic processlipid metabolic processvitamin metabolic processsulfur compound metabolic processintracellular protein transportnucleocytoplasmic transportautophagyinflammatory responsemitochondrion organizationcytoskeleton organizationmicrotubule-based movementperoxisome organizationlysosome organizationchromosome segregationcell adhesionestablishment or maintenance of cell polarityprogrammed cell deathphotosynthesismrna metabolic processsnrna metabolic processvesicle-mediated transportreproductive processdigestive system processsignalingcell differentiationprotein catabolic processextracellular matrix organizationregulatory ncrna-mediated gene silencingtelomere organizationcell junction organizationwound healingribosome biogenesiscilium organizationanatomical structure developmentcell motilitynervous system processendocrine processprotein maturationtransmembrane transportnucleobase-containing small molecule metabolic processhepaticobiliary system processmembrane organizationprotein-containing complex assemblycell wall organization or biogenesisnitrogen cycle metabolic processprotein localization to plasma membranedefense response to other organismdetoxificationmeiotic nuclear divisionmitotic nuclear divisionmitochondrial gene expressioncarbohydrate derivative metabolic processother biological processall cellular componentnuclear chromosomeextracellular regionextracellular spacecell wallnucleusnuclear envelopenucleoplasmchromosomenucleolusmitochondrionlysosomeendosomevacuoleperoxisomeendoplasmic reticulumgolgi apparatuslipid dropletmicrotubule organizing centercytosolribosomecytoskeletonplasma membraneciliumplastidthylakoidexternal encapsulating structureextracellular matrixcytoplasmic vesicleorganelleother cellular component
Cell color indicative of number of GO terms
AspectTerm
Cellular Componentexternal side of plasma membrane
Cellular Componentmembrane raft
Molecular Functioncoreceptor activity
Molecular FunctionMHC class II protein binding
Molecular FunctionMHC class II protein complex binding
Molecular Functionprotein tyrosine kinase binding
Biological Processadaptive immune response
Biological Processcell adhesion
Biological Processinterleukin-15-mediated signaling pathway
Biological Processpositive regulation of ERK1 and ERK2 cascade
Biological ProcessT cell differentiation
Biological ProcessT cell selection

Keywords

Names & Taxonomy

Protein names

  • Recommended name
    T-cell surface glycoprotein CD4
  • Alternative names
    • T-cell surface antigen T4/Leu-3
  • CD Antigen Name
    • CD4

Gene names

    • Name
      CD4

Organism names

  • Taxonomic identifier
  • Taxonomic lineage
    Eukaryota > Metazoa > Chordata > Craniata > Vertebrata > Euteleostomi > Mammalia > Eutheria > Euarchontoglires > Primates > Haplorrhini > Catarrhini > Cercopithecidae > Cercopithecinae > Macaca

Accessions

  • Primary accession
    P79184

Subcellular Location

Cell membrane
; Single-pass type I membrane protein
Note: Localizes to lipid rafts.

Features

Showing features for topological domain, transmembrane.

TypeIDPosition(s)Description
Topological domain26-396Extracellular
Transmembrane397-418Helical
Topological domain419-458Cytoplasmic

Keywords

PTM/Processing

Features

Showing features for signal, chain, disulfide bond, glycosylation, lipidation, modified residue.

TypeIDPosition(s)Description
Signal1-25
ChainPRO_000001462326-458T-cell surface glycoprotein CD4
Disulfide bond41↔109
Glycosylation42N-linked (GlcNAc...) asparagine
Disulfide bond155↔184
Glycosylation296N-linked (GlcNAc...) asparagine
Glycosylation325N-linked (GlcNAc...) asparagine
Disulfide bond328↔370
Lipidation419S-palmitoyl cysteine
Lipidation422S-palmitoyl cysteine
Modified residue433Phosphoserine
Modified residue440Phosphoserine
Modified residue456Phosphoserine

Post-translational modification

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

Keywords

PTM databases

Interaction

Subunit

Forms disulfide-linked homodimers at the cell surface. Interacts with LCK. Interacts with PTK2/FAK1. Binds to P4HB/PDI. Interacts with IL16; this interaction induces a CD4-dependent signaling in lymphocytes. Interacts (via Ig-like V-type domain) with MHCII alpha chain (via alpha-2 domain) and beta chain (via beta-2 domain); this interaction increases the affinity of TCR for peptide-MHCII. CD4 oligomerization via Ig-like C2-type 2 and 3 domains appears to be required for stable binding to MHCII and adhesion between T cells and APCs.

Structure

Family & Domains

Features

Showing features for domain.

TypeIDPosition(s)Description
Domain26-125Ig-like V-type
Domain126-203Ig-like C2-type 1
Domain204-317Ig-like C2-type 2
Domain318-374Ig-like C2-type 3

Domain

The Ig-like V-type domain mediates the interaction with MHCII.

Keywords

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Sequence processing
    The displayed sequence is further processed into a mature form.
  • Length
    458
  • Mass (Da)
    50,828
  • Last updated
    1997-05-01 v1
  • Checksum
    76B3E7EF08185535
MNRGIPFRHLLLVLQLALLPAVTQGKKVVLGKKGDTVELTCNASQKKNTQFHWKNSNQIKILGIQGSFLTKGPSKLSDRADSRKSLWDQGCFSMIIKNLKIEDSDTYICEVENKKEEVELLVFGLTANSDTHLLEGQSLTLTLESPPGSSPSVKCRSPGGKNIQGGRTISVPQLERQDSGTWTCTVSQDQKTVEFKIDIVVLAFQKASSTVYKKEGEQVEFSFPLAFTLEKLTGSGELWWQAERASSSKSWITFDLKNKEVSVKRVTQDPKLQMGKKLPLHLTLPQALPQYAGSGNLTLALEAKTGKLHQEVNLVVMRAAQFQENLTCEVWGPTSPKLTLSLKLENKGATVSKQAKAVWVLNPEAGMWQCLLSDSGQVLLESNIKVVPTWPTPVQPMALIVLGGVAGLLLFTGLGIFFCVRCRHRRRQAERMSQIKRLLSEKKTCQCPHRFQKTCSPI

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
D63348
EMBL· GenBank· DDBJ
BAA09672.1
EMBL· GenBank· DDBJ
mRNA

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