Larry Holmes defends his share of the heavyweight title tonight in Las Vegas against unranked James (Bonecrusher) Smith in a scheduled 15-round bout.

The International Boxing Federation title fight is the first bout for Holmes, 35, in nearly a year. Smith, 29, who has been a professional for three years, lost his first fight by knockout to James Broad before winning his next 14. . . . .

Five District boxers will be fighting for national championships tonight in Indianapolis. Alton Rice, Darryl Lattimore, Lyndon Walker, James Harris and Eugene Speed advanced to the finals of the USA Amateur Boxing Championships with victories last night.

Rice and Lattimore advanced to the finals of the 147-pound class with unanimous decisions over David Humphrey of Louisville and Billy Bridges of Lincolnton, N.C., respectively.

At 125 pounds, Walker needed only one round to earn his shot at the title when Chuck Richards of Rapid City, S.D., received three standing eight counts.

Harris won a unanimous decision over Michael Cardajal of Phoenix in the 106-pound class and Speed edged Paul Banke of Azusa, Calif., 3-2, to advance in the 119-pound class . . . .

Promoter Don King has embarrassed an anti-apartheid group to which he belongs by helping to send a heavyweight championship fight to Bophuthatswana, said former tennis star Arthur Ashe, co-chairman of Artists and Athletes Against Apartheid in an article in yesterday's New York Times.

King, who is black, had agreements with both Gerrie Coetzee and Greg Page to sell the promotional rights to Coetzee's World Boxing Association title defense against Page, a black American, to Sol Kerzner of South Africa for more than $1 million. They will fight Dec. 1 in Sun City.

King told the Times: "I'm against apartheid today, and I was against apartheid yesterday. I'm not going to South Africa. All I did was sell my rights.