The cellular internalization of recombinant gamma interferon differs from that of natural interferon gamma.
Purified natural and recombinant murine gamma interferons (MuIFN-gamma) bind at 4 degrees C to cultured L929 mouse fibroblasts with comparable receptor-binding affinity (Kd = 9 x 10(-10) M). Both 125I-labeled MuIFNs are rapidly internalized by cells at 37 degrees C, although recombinant IFN is internalized somewhat more slowly than natural IFN (t1/2 = 90 sec and 45 sec, respectively). Immunoelectronmicroscopy showed that the majority of bound recombinant MuIFN-gamma was located on the plasma membrane outside of coated areas, whereas natural interferon was found mainly in coated pits. At 37 degrees C most of the recombinant molecules entered the cytoplasm in pinocytotic vesicles, while natural interferon was internalized by the specific mechanism of receptor-mediated endocytosis [1]. However, nearly equal amounts of immunocytochemically detectable molecules of both IFNs were found in the cell nucleus within 2-3 min incubation at 37 degrees C. Thus, the process of translocation of the recombinant IFN-gamma appears to differ from that of the natural product.
Kushnaryov
V M
VM
Department of Microbiology, Medical College of Wisconsin, Milwaukee 53226.
MacDonald
H S
HS
Sedmak
J J
JJ
Grossberg
S E
SE
D000818:Animals; D001692:Biological Transport; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000378:metabolism; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004705:Endocytosis; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000493:pharmacokinetics*; D007739:L Cells / Q000378:metabolism; D051379:Mice; D011956:Receptors, Cell Surface / Q000378:metabolism; D011994:Recombinant Proteins
D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D007371:Interferon-gamma