Prominin-1, originally found on neuroepithelial stem cells in mice, is a five transmembrane domain cell-surface glycoprotein that localizes to membrane protrusions. Its homologue human Prominin-1 was first isolated from hematopoietic stem cells by a monoclonal antibody recognizing a specific epitope designated as AC133 (CD133). Transcription of Prominin-1 is driven by five tissue-specific alternative promoters resulting in the formation of differentially spliced mRNA isoforms. Prominin-1 is expressed on different types of stem cells, but it is not known if it plays a significant role in key stem cell functional features. Although the biological function of Prominin-1 is not well understood, the AC133 epitope currently serves as a useful marker for the isolation of hematopoietic and endothelial progenitor cells.
