Properties of immunoglobulin G-Fc receptors from neonatal rat intestinal brush borders.
Newborn rats acquire immunity passively by receptor-mediated uptake of maternal immunoglobulin G (IgG) from the first milk. Specific IgG binding to brush borders and IgG transport across the gut increase concomitantly for 10-12 days after birth and then fall until closure at about 21 days. Cortisol acetate administration accelerates this decline. Two classes of binding site are resolved by their affinities (KA1 = 1.3 X 10(8) M; KA2 = 5.15 X 10(6) M). Persistence of the low-affinity site after closure precludes a transport role (see Rodewald et al, this volume). Target size analysis gives a preliminary Mr for the high-affinity site of 90 000-100 000. IgG recognition involves a small number of positively charged residues in the Fc region. An Fc binding activity is solubilized from intestinal brush borders by lithium 3,5-diiodosalicylate.
D000818:Animals; D000831:Animals, Newborn; D001692:Biological Transport; D002417:Cattle; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007421:Intestine, Small / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism; D007700:Kinetics; D008871:Microvilli / Q000378:metabolism; D009994:Osmolar Concentration; D051381:Rats; D011961:Receptors, Fc; D017452:Receptors, IgG
D011961:Receptors, Fc; D017452:Receptors, IgG