Class I major histocompatibility complex molecules have been shown to be physically associated with insulin receptor molecules on the surfaces of a number of different cell types. The class I human leukocyte antigen (human MHC) phenotype of B lymphoblasts correlates with the affinity of IR for insulin. This correlation could be the result of association of some but not other HLA molecules with IR, or could reflect differences in the way in which association with an HLA molecule affects the function of IR. To distinguish between these possibilities, this study isolated complexes of four different class I HLA molecules with IR. Expression of some of these molecules correlates with high-affinity IR, whereas expression of others correlates with 5- to 10-fold lower affinity IR. This study found that chemical cross-linking was necessary to stabilize HLA-IR complexes, and all four of the class I HLA molecules studied, HLA-A1, HLA-A2, HLA-B5, and HLA-B8, can form complexes with IR.

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