Identification of the Receptor Used by the Ecotropic Mouse GLN Endogenous Retrovirus
Résumé
Approximately 10% of the mouse genome is composed of endogenous
retroviruses belonging to different families. In contrast to the situation in the human
genome, several of these families correspond to recent, still-infectious elements capable of encoding complete viral particles. The mouse GLN endogenous retrovirus is
one of these active families. We previously identified one fully functional provirus
from the sequenced genome of the C57BL/6 mouse strain. The GLN envelope protein gives the infectious viral particles an ecotropic host range, and we had demonstrated that the receptor was neither CAT1 nor SMIT1, the two previously identified
receptors for mouse ecotropic retroviral envelope proteins. In this study, we have
identified SLC19A1, the reduced folate carrier, as the cellular protein used as a receptor by the GLN retrovirus. The ecotropic tropism exhibited by this envelope is
due to the presence or absence of an N-linked glycosylation site in the first extracellular loop as well as the specific amino acid sequence of the extracellular domains of
the receptor. Like all the other retroviral envelope proteins from the gammaretrovirus genus whose receptors have been identified, the GLN envelope protein uses a
member of the solute carrier superfamily as a receptor.