Isolation of the haemopexin-haem receptor from pig liver cells

• Published in: FEBS letters 1986-04, Vol.199 (1), p.80-84
• Main Authors: Majuri, R., Gräsbeck, R.
• Format: Article
• Language: English
• Subjects: Affinity chromatography; Animals; Biological and medical sciences; Cell Membrane - analysis; Cell receptors; Cell structures and functions; Chromatography, Affinity; Chromatography, Gel; Chromatography, High Pressure Liquid; Fundamental and applied biological sciences. Psychology; haem, iron protoporphyrin IX; Heme; Heme - metabolism; Heme iron; Hemin - analogs & derivatives; hemopexin; Hemopexin - metabolism; Hemopexin isolation; Hemopexin receptor; hepatocytes; HSA, human serum albumin; Liver - analysis; Molecular and cellular biology; Pig liver membrane; pigs; plasma membranes; Receptors, Cell Surface - isolation & purification; Receptors, Cell Surface - metabolism; Sepharose - analogs & derivatives; Swine; TMBZ, 3,3',5,5'-tetramethylbenzidine
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(86)81227-3

Isolated pig liver plasma membranes interact specifically with the haemopexin-haem complex ( K d 4.4 × 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-polyacrylamide 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 haemo-pexin-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.