  In a model of supersymmetric SU(5) Grand Unification with a spatial dimension
described by the orbifold $S^1/(Z_2 \times Z_2')$, proton decay is naturally
suppressed at all orders. This is achieved by a suitable implementation of the
discrete symmetries on the brane. But baryon number violating interactions are
present in this model. We propose a few possible experimental tests of this
model which exploit the effect of the baryon number violating couplings on
low-energy observables like neutron-antineutron oscillations, double nucleon
decay into two kaons, hadronic decay widths of the $Z$ boson, and $t \bar t$
production cross-section in Run II of the Tevatron.
