CD9
CD9 (CD9 Molecule) is a Protein Coding gene. Diseases associated with CD9 include Cytomegalovirus Retinitis and Diphtheria. Among its related pathways are Response to elevated platelet cytosolic Ca2+ and Uptake and actions of bacterial toxins. Gene Ontology (GO) annotations related to this gene include integrin binding. An important paralog of this gene is TSPAN2.
Function
Integral membrane protein associated with integrins, which regulates different processes, such as sperm-egg fusion, platelet activation and aggregation, and cell adhesion (PubMed:8478605, PubMed:14575715, PubMed:18541721).
Present at the cell surface of oocytes and plays a key role in sperm-egg fusion, possibly by organizing multiprotein complexes and the morphology of the membrane required for the fusion (By similarity).
In myoblasts, associates with CD81 and PTGFRN and inhibits myotube fusion during muscle regeneration (By similarity).
In macrophages, associates with CD81 and beta-1 and beta-2 integrins, and prevents macrophage fusion into multinucleated giant cells specialized in ingesting complement-opsonized large particles (PubMed:12796480).
Also prevents the fusion between mononuclear cell progenitors into osteoclasts in charge of bone resorption (By similarity).
Acts as a receptor for PSG17 (By similarity).
Involved in platelet activation and aggregation (PubMed:18541721).
Regulates paranodal junction formation (By similarity).
Involved in cell adhesion, cell motility and tumor metastasis (PubMed:8478605, PubMed:7511626).
Biological Process
Cell adhesion Source: UniProtKB
Cellular response to low-density lipoprotein particle stimulus Source: UniProtKB
Fusion of sperm to egg plasma membrane involved in single fertilization Source: UniProtKB
Glial cell migration Source: FlyBase
Myoblast fusion involved in skeletal muscle regeneration Source: UniProtKB
Negative regulation of cellular component movement Source: UniProtKB
Negative regulation of platelet aggregation Source: UniProtKB
Paranodal junction assembly Source: UniProtKB
Platelet activation Source: UniProtKB
Platelet degranulation Source: Reactome
Receptor internalization Source: UniProtKB
Sperm-egg recognition Source: UniProtKB
Cellular Location
Extracellular exosome; Cell membrane; Membrane. Present at the cell surface of oocytes. Accumulates in the adhesion area between the sperm and egg following interaction between IZUMO1 and its receptor IZUMO1R/JUNO.
Topology
Cytoplasmic: 2-12
Helical: 13-33
Extracellular: 34-55
Helical: 56-76
Cytoplasmic: 77-87
Helical: 88-111
Extracellular: 112-195
Helical: 196-221
Cytoplasmic: 222-228
PTM
Palmitoylated at a low, basal level in unstimulated platelets. The level of palmitoylation increases when platelets are activated by thrombin (in vitro). The protein exists in three forms with molecular masses between 22 and 27 kDa, and is known to carry covalently linked fatty acids (PubMed:11959120). Palmitoylation by ZDHHC2 regulates CD9 expression, association with other tetraspanin family proteins and function in cell adhesion (PubMed:18508921).
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Datasheet