  The excited states of the proton emitter $^{151}$Lu were reinvestigated in a
recoil-decay tagging experiment at the Accelerator Laboratory of the University
of Jyv\"askyl\"a (JYFL). The level scheme built on the ground state of
$^{151}$Lu was updated with five new $\gamma$-ray transitions. Large-scale
shell model calculations were carried out to interpret the experimental level
scheme. It is found that the excitation energies of states above the $27/2^-$
and $23/2^+$ isomeric levels can be sensitive to excitations from $g_{7/2}$ and
$d_{5/2}$ to single-particle orbitals above $N=Z=64$.
