The hemopexin receptor on the cell surface of human polymorphonuclear leukocytes.

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Promyelocytic leukemia HL-60 cells can be induced to differen-tiate to granulocytes, under the conditions of cultures in the presence of dimethyl sulfoxide (DMSO). Examination of the binding of 125I-labeled hemopexin to DMSO-induced HL-60 cells showed that the density of hemopex-in receptors on the induced-cells was 1.35 times that on the uninduced cells. We proposed that a specific receptor for hemopexin was present on the plasma mem-branes of polymorphonuclear leukocytes (PMNs). The binding of human [125I]hemopexin to human PMNs at 4°C was saturable with time and with in-creasing concentrations of [125I]hemopexin. Scatchard analysis of the binding revealed the presence of approximately 5.7 x 104 binding sites per cell with an ap-parent dissociation constant (Kd) of 2.3 x 10-9 M. [125I]flemopexin was rapidly bound then dissociated from the cells after the release of heme, when the cells were incubated with radioactive hemopexin at 37°C. Incubation of the cells with the [59Fe]heme-hemopexin complex resulted in an accumulation of [59Fe]heme in the cells, with a temperature of 37°C but not that of 4°C. Oua-bain or NaF inhibited not only the binding of [125I]hemopexin to PMNs but also the uptake of [59Fe]heme from [59Fe]heme hemopexin by the cells. Neither NH4 Cl nor chloroquine inhibited the uptake. Detergent extracts of 125I-labeled PMNs were incubated with a hemopexin-coupled Sepharose CL-6B. A polypep-tide reacting with hemopexin-Sepharose was estimated to have a molecular weight of 80, 000, as determined by polyacrylamide gel electrophoresis, in the presence of sodium dodecylsulfate. We propose that PMNs take up heme from hemopexin, as mediated by the 80, 000 dalton receptor for hemopexin.
日本細胞生物学会の論文

The hemopexin receptor on the cell surface of human polymorphonuclear leukocytes.

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日本細胞生物学会 | 論文

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