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Symbol CD9 contributors: mct/shn - updated : 04-09-2017
HGNC name CD9 molecule
HGNC id 1709
conjugated GlycoP
interspecies ortholog to Cd9, Mus musculus
ortholog to Cd9, Rattus norvegicus
ortholog to CD9, Pan troglodytes
  • transmembrane 4 superfamily
  • tetraspanin (TM4SF) family
  • CATEGORY antigen
    SUBCELLULAR LOCALIZATION     plasma membrane
  • expressed in a specific membrane microdomain, called "lipid raft"
  • located intracellularly as well as in the plasma membrane at cell-cell contact sites and in long spike-like extensions, whereas cells in confluent cultures predominantly showed plasma membrane staining
  • basic FUNCTION
  • involved in platelet activation and agregation
  • integral membrane proteins that facilitate the organization of membrane and intracellular signaling molecules into dynamic signaling microdomains, tetraspanin-enriched microdomains (TEMs)
  • implicated in cell adhesion, motility and proliferation
  • playing a crucial role for cell fusion during osteoclastogenesis after activation of the RANK/RANKL system, through its expression in lipid rafts
  • inhibiting the proliferation and tumorigenicity of colon carcinoma cells
  • regulates the actin cytoskeleton by downregulating of the WASF2, through the WNT-independent signal pathway
  • essential for sperm-egg fusion , and
  • having a function in migration and adhesion of these cells
  • involved in the migration of retinal microvascular endothelial cells
  • its mobility and partitioning are both dependent on its palmitoylation and plasma membrane cholesterol
  • has a role in the maturation of transmembrane TGFA and its stabilization at the cell surface, and in the cell-surface distribution in polarized epithelial cells
  • role in the presentation of TGFA in epithelial and carcinoma cells, whose physiology is driven by ligand-induced EGFR activation
  • might have an important role that attenuates EGFR signaling (not only associates EGFR but also a new regulator, which may affect EGF-induced signaling in cancer cells)
  • plays roles in cell proliferation and attachment as well as engraftment and can be considered as a useful marker to predict the efficacy of adipose-derived mesenchymal stem cells
  • with CD63 ssociate with a type II phosphatidylinositol 4-kinase, PI4K55, in both resting and activated platelets
  • with CD63 and CD81 are all involved in multinucleated giant cells formation, but play distinct roles
  • plays stimulus-independent roles in angiogenesis
  • appears to, at least in part, contribute to the delocalization of integrins and MMP14, disruption of which may prevent angiogenesis
  • involved in the proliferation but not survival of relatively quiescent endothelial cells
  • CD9 expression on human germinal center (GC) -B cells may reflect the status of GC-B cell activation or differentiation
  • CD9 is a marker for plasma cells precursors (
  • normal muscle regeneration requires tight control of muscle cell fusion by tetraspanins CD9 and CD81
  • requirement of two spermatozoon factors, IZUMO1 and SPACA6, and two oocyte factors, CD9 and the IZUMO1R, has been proven in Sperm-egg fusion
  • IZUMO1 and C16orf92 on the sperm membrane and CD9 and IZUMO1R/FOLR4 on the oocyte membrane have been identified as fusion-required proteins
  • role of IZUMO1R and CD9 in PTK2B activation and actin remodeling at the sperm binding site
    a component
  • constituent of membrane glycoprotein
  • association with CD21 (CR2)
    small molecule
  • CD59
  • Heparin-binding EGF-like growth factor
  • CD63
  • NAG-2
  • CD19
  • alpha2, alpha3 and alpha5-integrins
  • colligin/Hsp47
  • FPRP
  • protein kinase C
  • EWI-2
  • c-kit receptor tyrosine kinase
  • CD36
  • CD81 and CD53
  • CD38/HLA-DR complex
  • ZDHHC2
  • TGFalpha
  • presumptive target for CELF1-mediated regulation
  • ALCAM directly associates with the tetraspanin CD9 on the leukocyte surface in protein complexes that also include the metalloproteinase ADAM17/TACE
  • cell & other
    Other regulated by CELF1 (directly controls CD9 expression)
    corresponding disease(s)
    Other morbid association(s)
    TypeGene ModificationChromosome rearrangementProtein expressionProtein Function
    tumoral     --low  
    in endometrioid adenocarcinoma and in squamous cell carcinoma of the head and neck with high grade and poor prognosis
    tumoral     --low  
    associated with the negative progression and metastasis outbreak of multiple cancer type, including prostate, breast, colon, non-small cell lung cancer, oral squamous cell carcinoma
    Variant & Polymorphism
    Candidate gene
    Therapy target
    inhibition of CD9 expression or function via intravitreous injections of siRNA-CD9 or anti-CD9 antibodies may provide a new therapeutic strategy for angiogenesis such as that observed in certain ocular diseases
  • CD9-/- mouse females displayed a severe reduction of fertility
  • litter size from CD9-/- mouse was less than 2% of that of the wild type
  • CD9 homozygous mutant mouse females were infertile