Folate receptor of human mammary adenocarcinoma.
Binding of 3H-folate to human mammary tumor homogenate was of a high-affinity type (K = 10(10) M-1) and displayed apparent positive cooperativity. Radioligand dissociation was slow at pH 7.4, but rapid at pH 3.5. As compared to methotrexate, 5-formyltetrahydrofolate acted as a strong inhibitor of radioligand binding. Gel chromatography of radioligand-labeled homogenate of tumor tissue revealed three peaks: a small > or = 110 kDa peak and two major peaks of folate-binding activity (M(r) approximately 25 kDa and M(r) approximately 100 kDa). Mammary tumor tissue showed immunostaining with rabbit antibodies against human milk folate binder. A parallel elevation in the concentrations of folate-binding protein and triglyceride in tumor tissue as compared to normal tissue adjacent to the tumor was compatible with the localization of folate-binding protein in the triglyceride-rich fraction of mammary gland homogenate.
Holm
J
J
Department of Clinical Chemistry, Central Hospital Nykøbing Falster, Denmark.
Hansen
S I
SI
Høier-Madsen
M
M
Søndergaard
K
K
Bzorek
M
M
D000230:Adenocarcinoma / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D001943:Breast Neoplasms / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D002352:Carrier Proteins / Q000032:analysis* / Q000378:metabolism; D002850:Chromatography, Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D058973:Folate Receptors, GPI-Anchored; D006801:Humans; D007150:Immunohistochemistry; D008970:Molecular Weight; D011869:Radioligand Assay; D011956:Receptors, Cell Surface; D014280:Triglycerides / Q000032:analysis / Q000378:metabolism; D014316:Tritium
D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D011956:Receptors, Cell Surface; D014280:Triglycerides; D014316:Tritium