Expression of haemopexin receptors by cultured human cytotrophoblast.
The expression of cell-surface haemopexin (Hx) receptors on human cytotrophoblasts was assessed by using four different Hx species purified from plasma: human Hx isolated by wheatgerm-affinity chromatography, human Hx isolated by haem-agarose-affinity chromatography and rabbit and rat Hx, also isolated by haem-agarose-affinity chromatography. About 3500-7000 high-affinity (Kd 0.34-0.85 nM) receptors per cell were measured by Scatchard-type analysis at 4 degrees C using human (species obtained by both methods) or rabbit 125I-labelled haem-Hx. Measured simultaneously, transferrin receptor number and affinity were 40,000/cell and 0.83 nM respectively. In contrast with transferrin receptors, the number of Hx receptors did not increase during 24 h in cytotrophoblast culture. Rat Hx showed no specific binding to human Hx receptors in cytotrophoblast cultures.
van Dijk
H P
HP
Department of Chemical Pathology, Erasmus Universiteit Rotterdam, The Netherlands.
Kroos
M J
MJ
Starreveld
J S
JS
van Eijk
H G
HG
Tang
S P
SP
Song
D X
DX
Muller-Eberhard
U
U
D000818:Animals; D002478:Cells, Cultured; D005260:Female; D006466:Hemopexin / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D011247:Pregnancy; D011817:Rabbits; D051381:Rats; D018000:Receptors, Peptide / Q000378:metabolism / Q000502:physiology*; D011990:Receptors, Transferrin / Q000378:metabolism; D013045:Species Specificity; D014327:Trophoblasts / Q000378:metabolism* / Q000648:ultrastructure*
D018000:Receptors, Peptide; D011990:Receptors, Transferrin; C047453:hemopexin receptor; D006466:Hemopexin