  We study a discrete stochastic model of a molecular motor. This discrete
model can be viewed as a \emph{minimal} ratchet model. We extend our previous
work on this model, by further investigating the constraints imposed by the
Fluctuation Theorem on the operation of a molecular motor far from equilibrium.
In this work, we show the connections between different formulations of the
Fluctuation Theorem. One formulation concerns the generating function of the
currents while another one concerns the corresponding large deviation function,
which we have calculated exactly for this model. A third formulation of FT
concerns the ratio of the probability of making one forward step to the
probability of making one backward step. The predictions of this last
formulation of the Fluctuation Theorem adapted to our model are in very good
agreement with the data of Carter and Cross [Nature, {\bf 435}, 308 (2005)] on
single molecule measurements with kinesin. Finally, we show that all the
formulations of FT can be understood from the notion of entropy production.
