Sequences in antibody molecules important forreceptor-mediated transport into the chicken egg yolk

Large quantities of antibodies are transported into the yolk of the chicken's egg. We have identified several regions within the antibody molecule important for its uptake into the egg yolk. An intact Fc and hinge region but not the Fc-associated carbohydrate are required for transport. Our data suggest that the C(H)2/C(H)3 interface is recognized by the receptor responsible for immunoglobulin (Ig) transport. At this interface, residues 251-254 form an exposed loop on the surface Of C(H)2. Chicken IgY (cIgY) hits the sequence LYIS and human IgG (hIgG) has the sequence LMIS at these positions; mutation of MIS to glycines results in an IgG that is not transported. A second site important for transport is at positions 429-432 within C(H)3. All transported antibodies have the sequence HEAL, whereas, murine IgG2b (mIgG2b) with the sequence HEGL and cIgA with the sequence HDGI fail to be transported. hIgA has the HEAL sequence and is transported. (C) 2002 Elsevier Science Ltd. All rights reserved.