A RECEPTOR FOR SUBGROUP-A ROUS-SARCOMA VIRUS IS RELATED TO THE LOW-DENSITY-LIPOPROTEIN RECEPTOR

Cellular receptors are required for efficient entry of retroviruses in to cells. We previously cloned a chicken gene responsible for suscepti bility to the retrovirus subgroup A Rous sarcoma virus (RSV(A)). Here we have isolated the quail homolog and generated two alternatively spl iced processed genes encoding cellular receptors for RSV(A). Predicted products of the processed genes appear to be small membrane-associate d proteins with identical 83 amino acid extracellular domains but diff erent membrane anchors. Within the extracellular domain is a region cl osely related to the ligand-binding repeat of the low density lipoprot ein receptor (LDLR). Expression of either processed gene renders mamma lian cells specifically susceptible to RSV(A). Antibodies directed aga inst the receptor block subgroup A infection of avian cells via endoge nous receptors and have no effect on entry of other RSV subgroups. Thu s, small LDLR-related proteins are cellular receptors for RSV(A).