CD9 Molecular Targets Information Overview

Molecular Name: CD9 molecule

Gene Family: Tetraspanin family (Transmembrane 4 superfamily/TM4SF) with four transmembrane structural domains.

Synonyms: MIC3, TSPAN29, MRP-1, BTCC-1, DRAP-27, GIG2, CD9 antigen.

Formerly known as: 5H9 antigen, T-cell surface antigen TSPAN-29, Leu6

CD9 Molecular Targets Overview

Molecular weight of 24-27 kD, widely distributed in pre-B lymphocytes, stromal cells, acidophagocytic granulocytes, basophagocytic granulocytes, platelets, endothelial cells, brain and peripheral neuronal cells, vascular smooth muscle, myocardium, and epithelial cells.CD9 Belongs to the tetraspanning (tetraspanning) family of membrane proteins (TM4 superfamily, i.e., TM4SF, this membrane protein crosses the cell membrane four times), whose ligands and related molecules are CD63, CD81, CD82, integrin β1, CD41/CD61 (platelet membrane glycoprotein IIb/IIIa), HB-EGF, pre-B-lymphocyte HLA- DR and PI4 kinase.

CD9 is associated with platelet aggregation and activation and is a co-receptor for diphtheria toxin. It upregulates heparinbinding epidermal growth factor (HB-EGF) activity, is involved in sperm-egg fusion, and is associated with integrin α6β1. It is negatively correlated with metastasis of certain tumors.

Clinically, CD9 is used for immunophenotyping of leukemias and lymphomas (90% of acute non-T-lymphoblastic leukemias, 20% of T-ALL, and all megakaryocytic leukemias show positivity). In autologous bone marrow transplantation, it can be used to remove leukemia cells for bone marrow blood purification. In idiopathic thrombocytopenic purpura (ITP), anti-CD9 autoantibodies are present. In acute lymphoblastic leukemia, free CD9 molecules are detected in the blood during proliferation of pre-B lymphocytes.