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CD9 molecule
Symbols CD9 ; BTCC-1; DRAP-27; MIC3; MRP-1; TSPAN-29; TSPAN29
External IDs OMIM143030 MGI88348 HomoloGene20420 GeneCards: CD9 Gene
RNA expression pattern
PBB GE CD9 201005 at tn.png
More reference expression data
Species Human Mouse
Entrez 928 12527
Ensembl ENSG00000010278 ENSMUSG00000030342
UniProt P21926 P40240
RefSeq (mRNA) NM_001769 NM_007657
RefSeq (protein) NP_001760 NP_031683
Location (UCSC) Chr 12:
6.31 – 6.35 Mb
Chr 6:
125.46 – 125.49 Mb
PubMed search [1] [2]

CD9 antigen is a protein that in humans is encoded by the CD9 gene.[1]

The protein encoded by this gene is a member of the transmembrane 4 superfamily, also known as the tetraspanin family. Most of these members are cell-surface proteins that are characterized by the presence of four hydrophobic domains. The proteins mediate signal transduction events that play a role in the regulation of cell development, activation, growth and motility.

CD9 is a cell surface glycoprotein that is known to complex with integrins and other transmembrane 4 superfamily proteins. It is found on the surface of exosomes. It can modulate cell adhesion and migration and also trigger platelet activation and aggregation. In addition, the protein appears to promote muscle cell fusion and support myotube maintenance.[2] This protein also seems to be a key part in the egg-sperm fusion during mammalian fertilization, as CD9 knocked-out mice gametes don't undergo fusion.[3] CD9 is located in the microvillar membrane of the oocytes and also appears to intervene in maintaining the normal shape of oocyte microvilli.[4]

See also[edit]


CD9 has been shown to interact with TSPAN4,[5] PTGFRN,[6][7] CD81,[8][9] CD117,[10] CD46,[11] CD29[8][12] and CD49c.[13][14]


  1. ^ Katz F, Povey S, Parkar M, Schneider C, Sutherland R, Stanley K, Solomon E, Greaves M (March 1984). "Chromosome assignment of monoclonal antibody-defined determinants on human leukemic cells". Eur J Immunol 13 (12): 1008–1013. doi:10.1002/eji.1830131211. PMID 6198179. 
  2. ^ "Entrez Gene: CD9 CD9 molecule". 
  3. ^ François Le Naour et al. (2000). "Severely Reduced Female Fertility in CD9-Deficient Mice". Science 287 (5451): 319–321. doi:10.1126/science.287.5451.319. PMID 10634790. 
  4. ^ Kathryn E. Runge et al. (2007). "Oocyte CD9 is enriched on the microvillar membrane and required for normal microvillar shape and distribution". Developmental Biology 304 (1): 317–325. doi:10.1016/j.ydbio.2006.12.041. PMID 17239847. 
  5. ^ Tachibana, I; Bodorova J; Berditchevski F; Zutter M M; Hemler M E (November 1997). "NAG-2, a novel transmembrane-4 superfamily (TM4SF) protein that complexes with integrins and other TM4SF proteins". J. Biol. Chem. (UNITED STATES) 272 (46): 29181–29189. doi:10.1074/jbc.272.46.29181. ISSN 0021-9258. PMID 9360996. 
  6. ^ Charrin, S; Le Naour F; Oualid M; Billard M; Faure G; Hanash S M; Boucheix C; Rubinstein E (April 2001). "The major CD9 and CD81 molecular partner. Identification and characterization of the complexes". J. Biol. Chem. (United States) 276 (17): 14329–37. doi:10.1074/jbc.M011297200. ISSN 0021-9258. PMID 11278880. 
  7. ^ Stipp, C S; Orlicky D; Hemler M E (February 2001). "FPRP, a major, highly stoichiometric, highly specific CD81- and CD9-associated protein". J. Biol. Chem. (United States) 276 (7): 4853–4862. doi:10.1074/jbc.M009859200. ISSN 0021-9258. PMID 11087758. 
  8. ^ a b Radford, K J; Thorne R F; Hersey P (May 1996). "CD63 associates with transmembrane 4 superfamily members, CD9 and CD81, and with beta 1 integrins in human melanoma". Biochem. Biophys. Res. Commun. (UNITED STATES) 222 (1): 13–18. doi:10.1006/bbrc.1996.0690. ISSN 0006-291X. PMID 8630057. 
  9. ^ Horváth, G; Serru V; Clay D; Billard M; Boucheix C; Rubinstein E (November 1998). "CD19 is linked to the integrin-associated tetraspans CD9, CD81, and CD82". J. Biol. Chem. (UNITED STATES) 273 (46): 30537–30543. doi:10.1074/jbc.273.46.30537. ISSN 0021-9258. PMID 9804823. 
  10. ^ Anzai, Naoyuki; Lee Younghee; Youn Byung-S; Fukuda Seiji; Kim Young-June; Mantel Charlie; Akashi Makoto; Broxmeyer Hal E (June 2002). "C-kit associated with the transmembrane 4 superfamily proteins constitutes a functionally distinct subunit in human hematopoietic progenitors". Blood (United States) 99 (12): 4413–4421. doi:10.1182/blood.V99.12.4413. ISSN 0006-4971. PMID 12036870. 
  11. ^ Lozahic, S; Christiansen D; Manié S; Gerlier D; Billard M; Boucheix C; Rubinstein E (March 2000). "CD46 (membrane cofactor protein) associates with multiple beta1 integrins and tetraspans". Eur. J. Immunol. (GERMANY) 30 (3): 900–907. doi:10.1002/1521-4141(200003)30:3<900::AID-IMMU900>3.0.CO;2-X. ISSN 0014-2980. PMID 10741407. 
  12. ^ Mazzocca, Antonio; Carloni Vinicio; Sciammetta Silvia; Cordella Claudia; Pantaleo Pietro; Caldini Anna; Gentilini Paolo; Pinzani Massimo (September 2002). "Expression of transmembrane 4 superfamily (TM4SF) proteins and their role in hepatic stellate cell motility and wound healing migration". J. Hepatol. (England) 37 (3): 322–330. doi:10.1016/S0168-8278(02)00175-7. ISSN 0168-8278. PMID 12175627. 
  13. ^ Park, K R; Inoue T; Ueda M; Hirano T; Higuchi T; Maeda M; Konishi I; Fujiwara H; Fujii S (March 2000). "CD9 is expressed on human endometrial epithelial cells in association with integrins alpha(6), alpha(3) and beta(1)". Mol. Hum. Reprod. (ENGLAND) 6 (3): 252–257. doi:10.1093/molehr/6.3.252. ISSN 1360-9947. PMID 10694273. 
  14. ^ Hirano, T; Higuchi T; Ueda M; Inoue T; Kataoka N; Maeda M; Fujiwara H; Fujii S (February 1999). "CD9 is expressed in extravillous trophoblasts in association with integrin alpha3 and integrin alpha5". Mol. Hum. Reprod. (ENGLAND) 5 (2): 162–167. doi:10.1093/molehr/5.2.162. ISSN 1360-9947. PMID 10065872. 

Further reading[edit]