ID   CD9_CHLAE               Reviewed;         228 AA.
AC   P30409;
DT   01-APR-1993, integrated into UniProtKB/Swiss-Prot.
DT   23-JAN-2007, sequence version 2.
DT   04-NOV-2026, entry version 117.
DE   RecName: Full=CD9 antigen {ECO:0000250|UniProtKB:P21926};
DE   AltName: Full=27 kDa diphtheria toxin receptor-associated protein {ECO:0000303|PubMed:1522113};
DE            Short=DRAP27 {ECO:0000303|PubMed:1522113};
DE   AltName: CD_antigen=CD9 {ECO:0000250|UniProtKB:P21926};
GN   Name=CD9 {ECO:0000250|UniProtKB:P21926};
OS   Chlorocebus aethiops (Green monkey) (Cercopithecus aethiops).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini;
OC   Cercopithecidae; Cercopithecinae; Chlorocebus.
OX   NCBI_TaxID=9534;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], AND SUBCELLULAR LOCATION.
RX   PubMed=1522113; DOI=10.1083/jcb.118.6.1389;
RA   Mitamura T., Iwamoto R., Umata T., Yomo T., Urabe I., Tsuneoka M.,
RA   Mekada E.;
RT   "The 27-kD diphtheria toxin receptor-associated protein (DRAP27) from vero
RT   cells is the monkey homologue of human CD9 antigen: expression of DRAP27
RT   elevates the number of diphtheria toxin receptors on toxin-sensitive
RT   cells.";
RL   J. Cell Biol. 118:1389-1399(1992).
CC   -!- FUNCTION: Integral membrane protein associated with integrins, which
CC       regulates different processes, such as sperm-egg fusion, platelet
CC       activation and aggregation, and cell adhesion (By similarity). Present
CC       at the cell surface of oocytes and plays a key role in sperm-egg
CC       fusion, possibly by organizing multiprotein complexes and the
CC       morphology of the membrane required for the fusion (By similarity). In
CC       myoblasts, associates with CD81 and PTGFRN and inhibits myotube fusion
CC       during muscle regeneration (By similarity). In macrophages, associates
CC       with CD81 and beta-1 and beta-2 integrins, and prevents macrophage
CC       fusion into multinucleated giant cells specialized in ingesting
CC       complement-opsonized large particles (By similarity). Also prevents the
CC       fusion between mononuclear cell progenitors into osteoclasts in charge
CC       of bone resorption (By similarity). Acts as a receptor for PSG17 (By
CC       similarity). Involved in platelet activation and aggregation (By
CC       similarity). Regulates paranodal junction formation (By similarity).
CC       Involved in cell adhesion, cell motility and tumor metastasis (By
CC       similarity). {ECO:0000250|UniProtKB:P21926,
CC       ECO:0000250|UniProtKB:P40240}.
CC   -!- SUBUNIT: Forms both disulfide-linked homodimers and higher
CC       homooligomers as well as heterooligomers with other members of the
CC       tetraspanin family. Interacts (via the second extracellular domain)
CC       with integrin ITGAV:ITGB3 (By similarity). Interacts with integrin
CC       ITGA6:ITGB1; interaction takes place in oocytes and is involved in
CC       sperm-egg fusion (By similarity). Part of integrin-tetraspanin
CC       complexes composed of CD81, beta-1 and beta-2 integrins in the membrane
CC       of monocyte/macrophages (By similarity). Interacts with CD63;
CC       identified in a complex with CD63 and ITGB3. Associates with CR2/CD21
CC       and with PTGFRN/CD9P1. Part of a complex composed of CD9, CD81, PTGFRN
CC       and IGSF8 (By similarity). Interacts directly with IGSF8. Interacts
CC       with PDPN; this interaction is homophilic and attenuates platelet
CC       aggregation and pulmonary metastasis induced by PDPN. Interacts (on T
CC       cell side) with CD81 at immunological synapses between antigen-
CC       presenting cells and T cells (By similarity).
CC       {ECO:0000250|UniProtKB:P21926, ECO:0000250|UniProtKB:P40240}.
CC   -!- SUBCELLULAR LOCATION: Cell membrane {ECO:0000269|PubMed:1522113};
CC       Multi-pass membrane protein {ECO:0000269|PubMed:1522113}. Membrane
CC       {ECO:0000269|PubMed:1522113}; Multi-pass membrane protein
CC       {ECO:0000269|PubMed:1522113}. Secreted, extracellular exosome
CC       {ECO:0000250|UniProtKB:P40240}. Note=Present at the cell surface of
CC       oocytes. Accumulates in the adhesion area between the sperm and egg
CC       following interaction between IZUMO1 and its receptor IZUMO1R/JUNO.
CC       {ECO:0000250|UniProtKB:P40240}.
CC   -!- PTM: Palmitoylated at a low, basal level in unstimulated platelets. The
CC       level of palmitoylation increases when platelets are activated by
CC       thrombin (in vitro). The protein exists in three forms with molecular
CC       masses between 22 and 27 kDa, and is known to carry covalently linked
CC       fatty acids. Palmitoylation by ZDHHC2 regulates CD9 expression,
CC       association with other tetraspanin family proteins and function in cell
CC       adhesion. {ECO:0000250|UniProtKB:P21926}.
CC   -!- SIMILARITY: Belongs to the tetraspanin (TM4SF) family. {ECO:0000305}.
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DR   EMBL; D10726; BAA01569.1; -; mRNA.
DR   PIR; A42929; A42929.
DR   AlphaFoldDB; P30409; -.
DR   SMR; P30409; -.
DR   DIP; DIP-181N; -.
DR   IntAct; P30409; 1.
DR   GlyCosmos; P30409; 2 sites, No reported glycans.
DR   SwissPalm; P30409; -.
DR   GO; GO:0070062; C:extracellular exosome; IEA:UniProtKB-ARBA.
DR   GO; GO:0005886; C:plasma membrane; ISS:UniProtKB.
DR   GO; GO:0005178; F:integrin binding; ISS:UniProtKB.
DR   GO; GO:0007155; P:cell adhesion; ISS:UniProtKB.
DR   GO; GO:0007342; P:fusion of sperm to egg plasma membrane involved in single fertilization; ISS:UniProtKB.
DR   GO; GO:0014905; P:myoblast fusion involved in skeletal muscle regeneration; ISS:UniProtKB.
DR   GO; GO:0090331; P:negative regulation of platelet aggregation; ISS:UniProtKB.
DR   GO; GO:0030913; P:paranodal junction assembly; ISS:UniProtKB.
DR   GO; GO:0007338; P:single fertilization; ISS:UniProtKB.
DR   GO; GO:0035036; P:sperm-egg recognition; ISS:UniProtKB.
DR   CDD; cd03152; CD9_LEL; 1.
DR   FunFam; 1.10.1450.10:FF:000016; Tetraspanin; 1.
DR   Gene3D; 1.10.1450.10; Tetraspanin; 1.
DR   InterPro; IPR042055; CD9_LEL.
DR   InterPro; IPR018499; Tetraspanin/Peripherin.
DR   InterPro; IPR000301; Tetraspanin_animals.
DR   InterPro; IPR018503; Tetraspanin_CS.
DR   InterPro; IPR008952; Tetraspanin_EC2_sf.
DR   PANTHER; PTHR19282:SF163; CD9 ANTIGEN; 1.
DR   PANTHER; PTHR19282; TETRASPANIN; 1.
DR   Pfam; PF00335; Tetraspanin; 1.
DR   PIRSF; PIRSF002419; Tetraspanin; 1.
DR   PRINTS; PR00259; TMFOUR.
DR   SUPFAM; SSF48652; Tetraspanin; 1.
DR   PROSITE; PS00421; TM4_1; 1.
PE   2: Evidence at transcript level;
KW   Cell adhesion; Cell membrane; Disulfide bond; Fertilization; Glycoprotein;
KW   Lipoprotein; Membrane; Palmitate; Secreted; Transmembrane;
KW   Transmembrane helix.
FT   CHAIN           1..228
FT                   /note="CD9 antigen"
FT                   /id="PRO_0000219203"
FT   TOPO_DOM        1..12
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        13..33
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        34..55
FT                   /note="Extracellular"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        56..76
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        77..87
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        88..111
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        112..195
FT                   /note="Extracellular"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        196..221
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        222..228
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   LIPID           9
FT                   /note="S-palmitoyl cysteine"
FT                   /evidence="ECO:0000250|UniProtKB:P21926"
FT   LIPID           78
FT                   /note="S-palmitoyl cysteine"
FT                   /evidence="ECO:0000250|UniProtKB:P21926"
FT   LIPID           79
FT                   /note="S-palmitoyl cysteine"
FT                   /evidence="ECO:0000250|UniProtKB:P21926"
FT   LIPID           87
FT                   /note="S-palmitoyl cysteine"
FT                   /evidence="ECO:0000250|UniProtKB:P21926"
FT   LIPID           218
FT                   /note="S-palmitoyl cysteine"
FT                   /evidence="ECO:0000250|UniProtKB:P21926"
FT   LIPID           219
FT                   /note="S-palmitoyl cysteine"
FT                   /evidence="ECO:0000250|UniProtKB:P21926"
FT   CARBOHYD        52
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   CARBOHYD        53
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   DISULFID        152..181
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00114"
FT   DISULFID        153..167
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00114"
SQ   SEQUENCE   228 AA;  25431 MW;  FBE3298BAFAF6B7A CRC64;
     MPVKGGTKCI KYLLFGFNFI FWLAGIAVLA IGLWLRFDSQ TKSIFEQETN NNNSSFYTGV
     YILIGAGALM MLVGFLGCCG AVQESQCMLG LFFGFLLVIF AIEIAAAIWG YSHKDEVIKE
     VQEFYKDTYN KLKTKDEPQR ETLKAIHYAL DCCGLAGGVE QFISDICPKK DVLETFTIKS
     CPDAIKEVFD NKFHIIGAVG IGIAVVMIFG MIFSMILCCA IRRNREMV
//