Characterization of prominin-2, a new member of the prominin family of pentaspan membrane glycoproteins.
Prominin/CD133 is a 115/120-kDa integral membrane glycoprotein specifically associated with plasma membrane protrusions in epithelial and non-epithelial cells including neuroepithelial and hematopoietic stem cells. Here we report the identification as well as molecular and cell biological characterization of mouse, rat, and human prominin-2, a 112-kDa glycoprotein structurally related to prominin (referred to as prominin-1). Although the amino acid identity between prominin-2 and prominin-1 is low (<30%), their genomic organization is strikingly similar, suggesting an early gene duplication event. Like prominin-1, prominin-2 exhibits a characteristic membrane topology with five transmembrane segments and two large glycosylated extracellular loops. Upon its ectopic expression in Chinese hamster ovary cells as a green fluorescent protein fusion chimera, prominin-2 was also found to be associated with plasma membrane protrusions, as revealed by its co-localization with prominin-1, suggesting a related role. Consistent with this, prominin-2 shows a similar tissue distribution to prominin-1, being highly expressed in the adult kidney and detected all along the digestive tract as well as in various other epithelial tissues. However, in contrast to prominin-1, prominin-2 was not detected in the eye, which perhaps explains why a loss-of function mutation in the human prominin-1 gene causes retinal degeneration but no other obvious pathological signs. Finally, we present evidence for the existence of a family of pentaspan membrane proteins, the prominins, which are conserved in evolution.
Fargeas
Christine A
CA
Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, D-01307 Dresden, Germany.
Florek
Mareike
M
Huttner
Wieland B
WB
Corbeil
Denis
D
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary; D020224:Expressed Sequence Tags; D005123:Eye / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D008562:Membrane Glycoproteins; C473222:PROM2 protein, human; C473220:Prom2 protein, mouse; C473221:Prom2 protein, rat; D012333:RNA, Messenger