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High affinity insulin binding by soluble insulin receptor extracellular domain fused to a leucine zipper
Author(s) -
Hoyne Peter A.,
Cosgrove Leah J.,
McKern Neil M.,
Bentley John D.,
Ivancic Neva,
Elleman Thomas C.,
Ward Colin W.
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01872-x
Subject(s) - ectodomain , leucine zipper , insulin receptor , receptor , chemistry , dissociation constant , insulin , biochemistry , insulin receptor substrate , transmembrane domain , fusion protein , biophysics , biology , peptide sequence , insulin resistance , endocrinology , recombinant dna , gene
Insulin receptors (IRs) that are truncated at the end of the ectodomain form dimers that bind insulin with different characteristics to wild type receptors. These soluble IRs have lowered affinity for insulin compared with full‐length IR, and exhibit linear Scatchard plots in contrast to the curvilinear plots obtained with full‐length IR, IR truncated at the C‐terminus of the transmembrane region and IR ectodomains fused to the self‐associating constant domains from Fc or λ immunoglobulins. In this report, we have fused the IR ectodomain to the 33 residue leucine zipper from the transcriptional activator GCN4 of Saccharomyces cerevisiae . This fusion protein binds insulin with high affinity in a manner comparable to native receptor. The respective dissociation constants were K d1 8.2×10 −11 M and K d2 1.6×10 −8 M for hIRedZip and K d1 5.7×10 −11 M and K d2 6.3×10 −9 M for membrane‐anchored, native receptor.