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P01732 · CD8A_HUMAN

  • Protein
    T-cell surface glycoprotein CD8 alpha chain
  • Gene
    CD8A
  • Status
    UniProtKB reviewed (Swiss-Prot)
  • Amino acids
  • Protein existence
    Evidence at protein level
  • Annotation score
    5/5

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 I molecule:peptide complex. The antigens presented by class I peptides are derived from cytosolic proteins while class II derived from extracellular proteins. Interacts simultaneously with the T-cell receptor (TCR) and the MHC class I proteins 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 cytotoxic T-lymphocytes (CTLs). This mechanism enables CTLs to recognize and eliminate infected cells and tumor cells. In NK-cells, the presence of CD8A homodimers at the cell surface provides a survival mechanism allowing conjugation and lysis of multiple target cells. CD8A homodimer molecules also promote the survival and differentiation of activated lymphocytes into memory CD8 T-cells.

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 Componentextracellular region
Cellular Componentplasma membrane
Cellular Componentplasma membrane raft
Cellular Componentreceptor complex
Cellular ComponentT cell receptor complex
Molecular Functioncoreceptor activity
Molecular FunctionMHC class I protein binding
Molecular FunctionMHC class I protein complex binding
Biological Processadaptive immune response
Biological Processantigen processing and presentation
Biological Processcell surface receptor protein tyrosine kinase signaling pathway
Biological Processcell surface receptor signaling pathway
Biological Processcytotoxic T cell differentiation
Biological Processimmune response
Biological ProcessT cell activation
Biological ProcessT cell mediated immunity
Biological ProcessT cell receptor signaling pathway

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    T-cell surface glycoprotein CD8 alpha chain
  • Alternative names
    • T-lymphocyte differentiation antigen T8/Leu-2
  • CD Antigen Name
    • CD8a

Gene names

    • Name
      CD8A
    • Synonyms
      MAL

Organism names

  • Taxonomic identifier
  • Taxonomic lineage
    Eukaryota > Metazoa > Chordata > Craniata > Vertebrata > Euteleostomi > Mammalia > Eutheria > Euarchontoglires > Primates > Haplorrhini > Catarrhini > Hominidae > Homo

Accessions

  • Primary accession
    P01732
  • Secondary accessions
    • B4DT80
    • D6W5M8
    • Q13970
    • Q4ZG17

Proteomes

Organism-specific databases

Subcellular Location

Isoform 1

Cell membrane
; Single-pass type I membrane protein
Note: CD8A localizes to lipid rafts only when associated with its partner CD8B.

Isoform 2

Secreted

Features

Showing features for topological domain, transmembrane.

Type
IDPosition(s)Description
Topological domain22-182Extracellular
Transmembrane183-203Helical
Topological domain204-235Cytoplasmic

Keywords

Disease & Variants

Involvement in disease

Immunodeficiency 116 (IMD116)

  • Note
    • The disease is caused by variants affecting the gene represented in this entry
  • Description
    An autosomal recessive immunologic defect characterized by absence of CD8+ cells, leading to recurrent bacterial infections.
  • See also
    MIM:608957
Natural variants in IMD116
Variant IDPosition(s)ChangeDescription
VAR_021020111G>Sin IMD116; prevents CD8 expression; dbSNP:rs121918660

Features

Showing features for natural variant, mutagenesis.

Type
IDPosition(s)Description
Natural variantVAR_021020111in IMD116; prevents CD8 expression; dbSNP:rs121918660
Mutagenesis111Prevents CD8 expression.
Mutagenesis206Complete loss of palmitoylation.

Variants

We now provide the "Disease & Variants" viewer in its own tab.

The viewer provides 342 variants from UniProt as well as other sources including ClinVar and dbSNP.

Go to variant viewer

Keywords

Organism-specific databases

Miscellaneous

Genetic variation databases

PTM/Processing

Features

Showing features for signal, chain, disulfide bond, lipidation.

Type
IDPosition(s)Description
Signal1-21
ChainPRO_000001463822-235T-cell surface glycoprotein CD8 alpha chain
Disulfide bond43↔115
Lipidation206S-palmitoyl cysteine

Post-translational modification

Palmitoylated, but association with CD8B seems to be more important for the enrichment of CD8A in lipid rafts.
O-glycosylated.
Phosphorylated in cytotoxic T-lymphocytes (CTLs) following activation.

Keywords

Proteomic databases

PTM databases

Expression

Tissue specificity

CD8 on thymus-derived T-cells usually consists of a disulfide-linked alpha/CD8A and a beta/CD8B chain. Less frequently, CD8 can be expressed as a CD8A homodimer. A subset of natural killer cells, memory T-cells, intraepithelial lymphocytes, monocytes and dendritic cells expresses CD8A homodimers. Expressed at the cell surface of plasmacytoid dendritic cells upon herpes simplex virus-1 stimulation.

Gene expression databases

Organism-specific databases

Interaction

Subunit

Forms disulfide-linked heterodimers with CD8B at the cell surface. Forms also homodimers in several cell types including NK-cells or peripheral blood T-lymphocytes. Interacts with the MHC class I HLA-A/B2M dimer. One HLA-A molecule (mainly via nonpolymorphic alpha-3 domain) interacts with one CD8A homodimer (via CDR-like loop) (PubMed:2784196, PubMed:9177355).
Interacts with LCK in a zinc-dependent manner. Interacts with HLA-G; this interaction is direct and might down-regulate T cell receptor signaling

Complex viewer

Protein-protein interaction databases

Miscellaneous

Family & Domains

Features

Showing features for domain.

TypeIDPosition(s)Description
Domain22-135Ig-like V-type

Keywords

Phylogenomic databases

Family and domain databases

Sequence & Isoforms

Align isoforms (3)
  • Sequence status
    Complete
  • Sequence processing
    The displayed sequence is further processed into a mature form.

This entry describes 3 isoforms produced by Alternative splicing.

P01732-1

This isoform has been chosen as the canonical sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.

  • Name
    1
  • Synonyms
    membrane, mCD8alpha
  • See also
    sequence in UniParc or sequence clusters in UniRef
  • Length
    235
  • Mass (Da)
    25,729
  • Last updated
    1986-07-21 v1
  • MD5 Checksum
    7E74731A8583EB61055862C16F8DDAF9
MALPVTALLLPLALLLHAARPSQFRVSPLDRTWNLGETVELKCQVLLSNPTSGCSWLFQPRGAAASPTFLLYLSQNKPKAAEGLDTQRFSGKRLGDTFVLTLSDFRRENEGYYFCSALSNSIMYFSHFVPVFLPAKPTTTPAPRPPTPAPTIASQPLSLRPEACRPAAGGAVHTRGLDFACDIYIWAPLAGTCGVLLLSLVITLYCNHRNRRRVCKCPRPVVKSGDKPSLSARYV

P01732-2

  • Name
    2
  • Synonyms
    secreted, sCD8alpha
  • See also
    sequence in UniParc or sequence clusters in UniRef
  • Differences from canonical
    • 172-209: VHTRGLDFACDIYIWAPLAGTCGVLLLSLVITLYCNHR → G

P01732-3

  • Name
    3
  • See also
    sequence in UniParc or sequence clusters in UniRef
  • Differences from canonical
    • 1-1: M → MRNQAPGRPKGATFPPRRPTGSRAPPLAPELRAKQRPGERVM

Computationally mapped potential isoform sequences

There is 1 potential isoform mapped to this entry

View all
EntryEntry nameGene nameLength
B8ZZZ4B8ZZZ4_HUMANCD8A198

Features

Showing features for alternative sequence.

TypeIDPosition(s)Description
Alternative sequenceVSP_0544381in isoform 3
Alternative sequenceVSP_012653172-209in isoform 2

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
M26315
EMBL· GenBank· DDBJ
AAA79217.1
EMBL· GenBank· DDBJ
Genomic DNA
M26313
EMBL· GenBank· DDBJ
AAA79217.1
EMBL· GenBank· DDBJ
Genomic DNA
M26314
EMBL· GenBank· DDBJ
AAA79217.1
EMBL· GenBank· DDBJ
Genomic DNA
M26315
EMBL· GenBank· DDBJ
AAA79218.1
EMBL· GenBank· DDBJ
Genomic DNA
M26313
EMBL· GenBank· DDBJ
AAA79218.1
EMBL· GenBank· DDBJ
Genomic DNA
M26314
EMBL· GenBank· DDBJ
AAA79218.1
EMBL· GenBank· DDBJ
Genomic DNA
M12824
EMBL· GenBank· DDBJ
AAA61133.1
EMBL· GenBank· DDBJ
mRNA
M12828
EMBL· GenBank· DDBJ
AAB04637.1
EMBL· GenBank· DDBJ
mRNA
M27161
EMBL· GenBank· DDBJ
AAA59674.1
EMBL· GenBank· DDBJ
Genomic DNA
AK300089
EMBL· GenBank· DDBJ
BAG61892.1
EMBL· GenBank· DDBJ
mRNA
AC064848
EMBL· GenBank· DDBJ
AAX88864.1
EMBL· GenBank· DDBJ
Genomic DNA
AC112696
EMBL· GenBank· DDBJ
-Genomic DNA No translation available.
CH471053
EMBL· GenBank· DDBJ
EAW99438.1
EMBL· GenBank· DDBJ
Genomic DNA
CH471053
EMBL· GenBank· DDBJ
EAW99439.1
EMBL· GenBank· DDBJ
Genomic DNA
CH471053
EMBL· GenBank· DDBJ
EAW99440.1
EMBL· GenBank· DDBJ
Genomic DNA

Genome annotation databases

Similar Proteins

Disclaimer

Any medical or genetic information present in this entry is provided for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care. Our staff consists of biologists and biochemists that are not trained to give medical advice.
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