An analysis of insulin receptor expression and binding on MHC class I positive and negative human lymphoblastoid cells.
Recent studies have demonstrated a specific membrane association between the polymorphic class I antigens of the MHC and the insulin receptor (IR). In some reports, variation in IR binding is attributed to the class I phenotype. To extend these observations, we have examined whether MHC class I products influence IR function, in particular, high affinity ligand-specific binding. Using two independent methods, we have compared IR affinity and density on a human B-lymphoblastoid cell line expressing HLA-A, -B products vs a null mutant and a set of transfectants where HLA-A3, -B7, or -Bw58 expression has been restored through gene transfer. The results from radioreceptor assay and RIA measuring IR binding and expression indicate that although there is a decrease in high affinity insulin binding sites in the HLA-A, -B null mutant, ligand binding cannot be restored in the transfectants expressing HLA-A or -B alleles. We conclude that the MHC class I products do not determine the insulin-binding phenotype of the cells examined in this study. Alternatively, we propose that insulin receptor heterogeneity in affinity and density may be influenced by other undetermined factors inherent to clonally expanded cells, thereby complicating dissection of IR/MHC interactions.
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
T
T
Liegler
J
J
Alexander
P
P
Cresswell
I
I
Goldfine
R S
RS
Goodenow
D002460:Cell Line; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism*; D009154:Mutation; D011863:Radioimmunoassay; D011869:Radioligand Assay; D011972:Receptor, Insulin / Q000378:metabolism*; D011994:Recombinant Proteins; D014162:Transfection
D015395:Histocompatibility Antigens Class I; D007328:Insulin; D011994:Recombinant Proteins; D011972:Receptor, Insulin