Identification and characterization of a promiscuous chemokine-binding protein in a XXXX erythroleukemic cell line.

@entity1 @entity5737 @entity3965 @entity2851 @entity2842 @entity20363 @entity687 @entity320 @entity214 @entity436
The erythrocyte @entity436 is a cell surface protein that binds a wide array of chemokines including @entity687 ( @entity687 ), @entity320 growth stimulating activity ( @entity2851 ), @entity2842 ( @entity2842 ), and @entity5737 (Regulated on Activation, Normal T Expressed and Secreted). This protein has also been identified as the Duffy blood group antigen, a cell surface receptor for the malarial parasite @entity3965 . In the present study, we have identified a @entity436 -like binding protein in a @entity1 erythroleukemic cell line (HEL), which, based on its molecular properties, may be related to the erythrocyte @entity436 . Saturation binding studies with 125I- @entity687 revealed a single class of @entity687 binding sites in HEL cells with a KD of 7.4 +/- 1.9 nM and a receptor density of 12,818 +/- 965 binding sites/cell. In competition studies unlabeled @entity687 @entity2851 , @entity2842 , and @entity5737 were fully able to inhibit the binding of 125I- @entity687 to HEL cells. Chemical cross-linking with radiolabeled @entity687 resulted in a cross-linked species of 60 kDa in membranes from HEL cells. The labeling was specific since it was inhibited by pre-incubation with 1 microM unlabeled @entity687 or @entity2851 . A monoclonal antibody (Fy6) to the @entity1 erythrocyte Duffy blood group antigen/ @entity436 blocked the binding of @entity687 and other chemokines to the HEL cell @entity436 -like binding protein. Cell membranes from HEL cells and from erythrocyte ghosts were subjected to @entity214 -PAGE and analyzed by Western blotting with anti-Fy6. The antibody bound to a molecule with a molecular mass of 50 kDa in HEL cell membranes and 40 kDa in erythrocyte ghosts. Northern blot analysis of mRNA revealed that the HEL chemokine-binding protein hybridized to a cDNA probe to the @entity20363 .
