  We calculate order $\alpha_s$ color magnetic corrections to the valence quark
distributions of the proton using the Los Alamos Model Potential wavefunctions.
The spin-spin interaction breaks the model SU(4) symmetry, providing a natural
mechanism for the difference between the up and down distributions. For a value
of $\alpha_s$ sufficient to produce the $N-\Delta$ mass splitting, we find up
and down quark distributions in reasonable agreement with experiment.
