CD133 (also known as prominin-1) is a glycoprotein with 5 transmembrane domains which localize to cellular protrusions. CD133 is expressed in hematopoietic stem cells, endothelial progenitor cells, glioblastoma, neuronal and glial stem cells, various pediatric brain tumors, as well as adult kidney, mammary glands, trachea, salivary glands, uterus, placenta, digestive tract, testes, and some other cell types. CD133 has been extensively used as a stem cell marker for normal and cancerous tissues.
Anti-CD133-SAP is a bonded toxin between a biotinylated rat monoclonal CD133 antibody and the secondary conjugate Streptavidin-ZAP containing the ribosome-inactivating protein, saporin. It specifically eliminates cells expressing CD133 in mice.