HOUSTON -- Yolanda King, the Rev. Martin Luther King Jr.'s eldest child who pursued her father's dream of racial harmony through drama and motivational speaking, collapsed and died. She was 51.

"She came from a family that encouraged social and personal change," said Dr. Melanie Wilson Lawson of Texas Southern University.

King was scheduled to participate in several events in Houston later this week. Lawson planned to host a book signing in her home.

"This was a wonderful opportunity to just let people know what it is that she's doing to continue the legacy after the loss of her father and then her mother," Lawson said.

King died late Tuesday in Santa Monica, Calif., said Steve Klein, a spokesman for the King Center. The family did not know the cause of death, but relatives think it might have been a heart problem, he said.

Lawson said she looked forward to meeting King for the first time and helping her promote her mission in life.

"That was to help people find greater peace and she really wanted to help empower people," Lawson said.

Former Mayor Andrew Young, a lieutenant of her father's who has remained close to the family, said King was going to her brother Dexter's home when she collapsed in the doorway.

Her death came less than a year and a half after her mother, Coretta Scott King, died in January 2006 after battling ovarian cancer and the effects of a stroke. Her struggle prompted her daughter to work with the American Heart Association to raise awareness about strokes, especially among blacks.

Yolanda King, who lived in California, was an actress, ran a production company and appeared in numerous films, including "Ghosts of Mississippi." She played Rosa Parks in the 1978 miniseries "King."

Yolanda King founded and led Higher Ground Productions, billed as a "gateway for inner peace, unity and global transformation." On her company's Web site, she described her mission as encouraging personal growth and positive social change.

Lawson said King inspired her to become a professor.

"She just radiates a sense of purpose and she's very committed to this nation," Lawson said.

The flag at The King Center, where she was a board member, flew at half-staff on Wednesday.

She was just two weeks old when Rosa Parks refused to give up her seat on a bus there, leading to the Montgomery bus boycott spearheaded by her father.

She was 12 when her father was assassinated in Memphis, Tenn., in 1968.

King was a 1976 graduate of Smith College in Northampton, Mass., where she majored in theater and Afro-American studies. She also earned a master's degree in theater from New York University.

Funeral arrangements would be announced later, the family said in a brief statement.

Lawson said the party planned at her home will go on to celebrate King's life.