  The production of $\eta'$ mesons in the reactions $\gamma p\to p\eta'$ and
$pp\to pp\eta'$ is described consistently within a relativistic meson exchange
model of hadronic interactions. The photoproduction can be described quite well
over the entire energy range of available data by considering an $S_{11}$ and a
$P_{11}$ resonance, in addition to the $t$-channel mesonic current. The
observed angular distribution is due to the interference between the
$t$-channel and the nucleon resonance $s$- and $u$-channel contributions. Our
analysis yields positions close to 1650 MeV and 1870 MeV for the $S_{11}$ and
$P_{11}$ resonances, respectively. We argue that, at present, identifying these
states with the known $S_{11}(1650)$ resonance and the missing $P_{11}$
resonance predicted at 1880 MeV, respectively, would be premature. It is found
that the nucleonic current is relatively small and that the $NN\eta^\prime$
coupling constant cannot be much larger than $g_{NN\eta^\prime}=3$. As for the
$p p \to p p \eta^\prime$ reaction, different current contributions are
constrained by a combined analysis of this and the photoproduction reaction.
Difficulties to simultaneously account for the 47-MeV and 144-MeV angular
distributions measured by the COSY-11 and DISTO collaborations, respectively,
are addressed.
