prominin-1; antigen AC133; prominin-like protein 1; CD133 (PROM1, PROML1, MSTP061)

Function

• binds cholesterol in cholesterol-containing plasma membrane microdomains
• role in apical plasma membrane organization of epithelial cells (putative)
• during early retinal development, regulates disk morphogenesis
• role in regulation of MAPK & Akt signaling pathways
• in neuroblastoma cells suppresses cell differentiation including neurite outgrowth (RET-dependent)
• interacts with CDHR1 & with actin filaments

Structure

• isoform 1 & isoform 2 are glycosylated
• belongs to the prominin family

Compartment

• cell projection, cilium, photoreceptor outer segment (putative)
• multi-pass membrane protein
• isoform 1:
  • apical cell membrane
  • cell projection, microvillus
• isoform 2: cell membrane

Alternative splicing

named isoforms=2

Expression

• isoform 1
  • selectively expressed on CD34-positive hematopoietic stem cells & progenitor cells in adult & fetal bone marrow, fetal liver, cord blood & adult peripheral blood
  • also expressed in a number of non-lymphoid tissues including retina, pancreas, placenta, kidney, liver, lung, brain & heart.
  • found in saliva within small membrane particles.
  • not detected on other blood cells
• isoform 2
  • predominantly expressed in fetal liver, skeletal muscle, kidney, & heart as well as adult pancreas, kidney, liver, lung, & placenta
  • highly expressed in fetal liver
  • low expression in bone marrow
  • very low expression in peripheral blood
  • expressed on hematopoietic stem cells & in epidermal basal cells (at protein level)

Pathology

• defects in PROM1 are the cause of
  • retinitis pigmentosa type 41
  • cone-rod dystrophy type 12
  • Stargardt disease type 4
  • retinal macular dystrophy type 2

Laboratory

• used as marker for hematopoietic progenitor cells for somatic stem cell isolation

More general terms

• CD antigen
• glycoprotein
• transmembrane 5 protein
• phosphoprotein
• human longevity protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=8842
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:8842
• OMIM: https://mirror.omim.org/entry/603786
• OMIM: https://mirror.omim.org/entry/604365
• OMIM: https://mirror.omim.org/entry/608051
• OMIM: https://mirror.omim.org/entry/612095
• OMIM: https://mirror.omim.org/entry/612657
• UniProt: http://www.uniprot.org/uniprot/O43490.html