title: Basic somatomedin (B-SM) receptors in human term placenta explants.
abstract: Binding of basic somatomedin (B-SM) and effect on alpha-aminoisobutyrate (AIB) uptake was studied in explants of term human placenta. B-SM demonstrated specific binding to the cultured explants. The binding was weakly inhibited by insulin. No significant degradation of the hormone was observed during incubation. The affinity cross-linking of [125I]B-SM binding to the explant membrane revealed a binding subunit of Mr 140 K. Addition of B-SM to the serum free medium stimulated the placental explant AIB uptake in a dose dependent manner. The incubated media containing FBS had less SM activity than the pre-incubated medium. The serum free incubated media did not contain measurable SM activity. The above findings that placental explants bind and have biological response to B-SM but do not produce B-SM suggest that SM has an endocrine rather than a paracrine action on human placenta.
mesh_terms: D000621:Aminoisobutyric Acids / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D009924:Organ Culture Techniques; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011956:Receptors, Cell Surface / Q000302:isolation & purification / Q000378:metabolism*; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000378:metabolism*
chemical_list: D000621:Aminoisobutyric Acids; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013002:Somatomedins; C100049:2-aminoisobutyric acid