  We study colored Higgsino-mediated proton decay (dimension-five proton decay)
in a model based on the flipped $SU(5)$ GUT. In the model, the GUT-breaking
${\bf10}$, ${\bf \overline{10}}$ fields have a GUT-scale mass term and gain
VEVs through higher-dimensional operators, which induces an effective mass term
between the color triplets in the ${\bf 5}$, ${\bf \bar{5}}$ Higgs fields that
is not much smaller than the GUT scale. This model structure gives rise to
observable dimension-five proton decay, and at the same time achieves moderate
suppression on dimension-five proton decay that softens the tension with the
current bound on $\Gamma(p\to K^+\nu)$. We investigate the flavor dependence of
the Wilson coefficients of the operators relevant to dimension-five proton
decay, by relating them with diagonalized Yukawa couplings and CKM matrix
components in MSSM, utilizing the fact that the GUT Yukawa couplings are in
one-to-one correspondence with the MSSM Yukawa couplings in flipped models.
Then we numerically evaluate the Wilson coefficients, and predict the
distributions of the ratios of the partial widths of various proton decay
modes.
