title: Macromolecule transfer in the human trophoblast: transcobalamin II-vitamin B12 uptake.
abstract: The accumulation of the large and hydrophilic IgG, TC II-B12 and B12 molecules is demonstrated for the first time in a human placental system which has metabolic and physiological functions. A trypsin-sensitive component is present in the human term placental uptake of TC II-B12, for which a placental membrane receptor has been previously identified; this component is absent for the accumulation of free B12, which has no known receptor. Analyses of the cytosol and incubation media indicate degradation, binding and release of TC II-B12 and B12 as TC II-B12, free B12 and TC I-like complexes. It is suggested that the human placental tissue slice be used for studies involving the binding, uptake and processing of macromolecules as exemplified by TC II-B12.
mesh_terms: D001798:Blood Proteins / Q000378:metabolism*; D002850:Chromatography, Gel; D003600:Cytosol / Q000032:analysis; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D066298:In Vitro Techniques; D011247:Pregnancy; D013997:Time Factors; D014155:Transcobalamins / Q000378:metabolism*; D014327:Trophoblasts / Q000378:metabolism*; D014357:Trypsin / Q000494:pharmacology; D014805:Vitamin B 12 / Q000378:metabolism*
chemical_list: D001798:Blood Proteins; D007074:Immunoglobulin G; D014155:Transcobalamins; D014357:Trypsin; D014805:Vitamin B 12