EXCLUSIVE
Reverend Al Sharpton is calling for the NBA to investigate Donald Sterling ASAP -- telling TMZ Sports, "No one should be allowed to own a team if they have in fact engaged in this kind of racial language."
Sharpton is calling for the league to make an investigation into Sterling its #1 priority -- adding, "We are prepared at National Action Network to rally in front of the NBA headquarters if this matter is not immediately dealt with."
TMZ Sports broke the story ... Sterling -- who owns the L.A. Clippers -- went off on his girlfriend for hanging out with black people in public and told her NOT to bring black people to his games.