CD133

CD133, also known as prominin-1 and encoded by the PROM1 gene, is a cell surface glycoprotein that has become widely used as a marker to identify and isolate stem and progenitor cells in various tissues. The protein is detected on the surface of several cell types, including hematopoietic stem cells, neural progenitor cells, and epithelial cells, as well as in a range of cancer cells. In research, antibodies against CD133, such as AC133, are used to enrich CD133-positive populations for functional studies.

Structurally, CD133 is a pentaspan transmembrane glycoprotein, featuring five transmembrane domains and two large extracellular loops, with cytoplasmic N- and C- termini. Expression and detection often depend on specific glycosylation patterns, so antibody recognition can vary with cellular state and death, and CD133 can be present on cells that do not display stem-like properties. Consequently, CD133 serves as a marker rather than a universal indicator of stemness.

Functionally, the precise role of prominin-1 remains incompletely understood. It is implicated in membrane organization, lipid raft composition, and maintenance of cell polarity, and may contribute to processes such as ciliogenesis in some cell types. Its role in controlling proliferation or differentiation appears context-dependent.

Clinical relevance is most prominent in cancer biology, where CD133 positivity has been associated with cancer stem cell–like properties and tumor-initiating capacity in glioblastoma, colorectal, pancreatic, and other cancers. In hematology, CD133 is used to enrich hematopoietic stem cells for transplantation. Ongoing debates address the specificity and stability of CD133 as a stem cell marker across tissue types.