Protons and neutrons are all part of a class of particles called hadrons. These hadrons are composed of yet smaller particles called which stick together in either 3s or pairs in order to create these particles.
There are 6 different types of quarks: 3 'up-type' quarks called up, charm and top and 3 'down type quarks called down, strange and bottom. The charge of the up type quarks is 2/3 that of the proton and electron, whilst the down type quarks are -1/3.
To make a proton, 3 of the quarks stick together, 2 up quarks and a down quark. The 'negative charge' you talk about is likely the -1/3 charge of the down quark in the proton.
yes they do have some sub particles called 'QUARKS' which are of following types:
protons are made of 2 up and 1 down quarks so the net charge is
charge= +2/3 + +2/3 -1/3