  I calculate the quark contributions to the axial and tensor charges and the
spin structure of the proton. The result indicates that the valence current
quark spins carry 1/3 of the proton spin, the total contribution of quark spins
to the proton spin satisfies $\Delta \Sigma = 1/3 + \Delta \Sigma_{sea} \le
1/3$, and the quarks (their spin plus orbital contributions) contribute about
one half of the proton spin at scale of 1 $GeV$. The valence current quark
contributions to the proton tensor charge are also obtained.
