In the present study, we attempted to determine the importance of a 23-amin
o-acid sequence within the carboxyl terminus of the human insulin receptor
(IR) molecule in modulating insulin action in Chinese hamster ovary cells.
Stable expression of a minigene encoding the receptor fragment led to an in
crease in insulin-induced IR autophosphorylation that was 2.4-fold higher w
hen compared to that of IR-expressing cells transfected with empty vector.
Insulin-stimulated downstream signaling was also significantly elevated in
cells expressing the minigene. It was found that expression of the minigene
had no effect toward insulin-like growth factor I receptor kinase activity
and function. These results indicate that the IR carboxyl terminus contain
s a motif that acts as a physiologic modulator of insulin signaling. Publis
hed 2000 Wiley-Liss, Inc.(dagger).