title: A novel five-transmembrane hematopoietic stem cell antigen: isolation, characterization, and molecular cloning.
abstract: Phenotypic analysis of hematopoietic stem and progenitor cells (HSCs) has been an invaluable tool in defining the biology of stem cell populations. We have recently described the production of AC133, a monoclonal antibody (MoAb) that binds to a novel cell surface antigen present on a CD34(bright) subset of human HSCs. This antigen is a glycosylated protein with a molecular weight of 120 kD. Here, we report the molecular cloning of a cDNA encoding this antigen and show that it does not share homology with any previously described hematopoietic or other cell surface antigen(s). The AC133 polypeptide has a predicted size of 97 kD and contains five-transmembrane (5-TM) domains with an extracellular N-terminus and a cytoplasmic C-terminus. Whereas the expression of tetraspan (4-TM) and 7-TM molecules is well documented on mature and immature hematopoietic cells and leukocytes, this 5-TM type of structure containing two large (255-amino acid [aa] and 290-aa) extracellular loops is unique and does not share sequence homology with any known multi-TM family members. Expression of this protein appears limited to bone marrow in normal tissue by immunohistochemical staining; however, Northern analysis suggests that the mRNA transcript is present in a variety of tissues such as the kidney, pancreas, placenta, and fetal liver. The AC133 antigen is also expressed on subsets of CD34+ leukemias, suggesting that it may be an important early marker for HSCs, as well as the first described member of a new class of TM receptors.
authors.affiliation: AmCell Corp, Sunnyvale, CA 94089, USA.
authors.forename: S
authors.initials: S
authors.lastname: Miraglia
authors.forename: W
authors.initials: W
authors.lastname: Godfrey
authors.forename: A H
authors.initials: AH
authors.lastname: Yin
authors.forename: K
authors.initials: K
authors.lastname: Atkins
authors.forename: R
authors.initials: R
authors.lastname: Warnke
authors.forename: J T
authors.initials: JT
authors.lastname: Holden
authors.forename: R A
authors.initials: RA
authors.lastname: Bray
authors.forename: E K
authors.initials: EK
authors.lastname: Waller
authors.forename: D W
authors.initials: DW
authors.lastname: Buck
mesh_terms: D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D018952:Antigens, CD34 / Q000032:analysis*; D000943:Antigens, Differentiation / Q000032:analysis; D000954:Antigens, Surface / Q000235:genetics / Q000302:isolation & purification*; D001483:Base Sequence; D019556:COS Cells; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D006412:Hematopoietic Stem Cells / Q000737:chemistry*; D006801:Humans; D007938:Leukemia / Q000276:immunology; D008562:Membrane Glycoproteins; D008969:Molecular Sequence Data; D009244:NAD+ Nucleosidase / Q000032:analysis; D012175:Retinoblastoma / Q000737:chemistry; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D000943:Antigens, Differentiation; D000954:Antigens, Surface; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D009244:NAD+ Nucleosidase; D051997:ADP-ribosyl Cyclase 1