  The deuteron disintegration process with the emission of fast proton in the
vicinity of the kinematical boundary of the reaction, when Feynman variable
$x\to 2$, is studied. The consideration is fulfilled in the framework of the
quark-parton model of cumulative phenomena based on perturbative QCD
calculations of the corresponding quark diagrams near the thresholds, at which
some quarks ("donors") in the nuclear flucton transfer all their longitudinal
momenta to the distinguished active quarks and become soft. The presence of the
multi-quark $6q$-configuration in a deuteron is essentially exploited in the
consideration. The different versions of hadronization mechanisms of the
produced cumulative quarks into cumulative particles are analyzed. It is shown
that in the case of the production of cumulative protons from deuteron the
hadronization through the coalescence of three cumulative quarks is favorable
and leads to the $(2-x)^5$ cross section threshold behavior whereas the usual
hadronization through one cumulative quark fragmentation into proton the same
as the calculations predicts for the deuteron structure function $F^d_2(x)$ at
$x\to 2$ in DIS processes. The results of the calculations are compared with
the available experimental data.
