  We consider the conformal dimension of an operator with large spin, using a
spinning D3-brane with electric flux in AdS_5 x S^5 instead of spinning
fundamental string. This spinning D3-brane solution seems to correspond to an
operator made by taking trace in a large symmetric representation. The
conformal dimension, the spin and the R-charge show a scaling relation in a
certain region of parameters. In the small string charge limit, the result is
consistent with the fundamental string picture. There is a phase transition
when the fundamental string charge become larger than a certain critical value;
there is no stable D3-brane solution above the critical value.
