Isolation of the haemopexin-haem receptor from pig liver cells.
Isolated pig liver plasma membranes interact specifically with the haemopexin-haem complex (Kd 4.4 X 10(-7) M). Affinity chromatography was used to isolate a membrane component which binds this complex with high affinity. Pig serum haemopexin was first isolated by affinity chromatography on haemin-Sepharose followed by HPLC gel filtration. Liver membranes solubilized with Triton X-100 were incubated with haemin-Sepharose saturated with haemopexin, and as a control, with affinity gel lacking haemopexin. SDS-poly-acrylamide gel electrophoresis of the eluted protein indicated that from the haemin-Sepharose emerglow-molecular-mass haemin-binding proteins whereas the eluate from haemopexin-haemin-Sepharose contained an additional 71 kDa protein, which did not bind free haemin. This protein appears to represent the haemopexin-haem receptor or a part of it. Haem from the haemopexin complex, as also free haemin, was accepted by a binder in the plasma membrane, which in gel filtration behaved like an 80 kDa molecule. This component probably represents a second functional subunit of the haemopexin-haem receptor.
D000818:Animals; D002462:Cell Membrane / Q000032:analysis; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D006418:Heme / Q000378:metabolism; D006427:Hemin / Q000031:analogs & derivatives*; D006466:Hemopexin / Q000378:metabolism; D008099:Liver / Q000032:analysis*; D011956:Receptors, Cell Surface / Q000302:isolation & purification* / Q000378:metabolism; D012685:Sepharose / Q000031:analogs & derivatives; D013552:Swine
D011956:Receptors, Cell Surface; C028027:heme receptor; C034982:hemin-sepharose; D006418:Heme; D006427:Hemin; D012685:Sepharose; D006466:Hemopexin