Quark distributions and nucleon spin structure

In this paper we calculate spin dependence of parton distributions and proton structure function. The polarized valon distributions in a proton and the polarized parton distributions inside the valon are necessary to obtain the polarized parton distributions in a proton. The results of our calculations for the proton structure function, xg(1)(p) are in good agreement with the available experimental data. We obtain the spin contribution and angular momentum of the valons to the proton.