STUDIO CITY, Calif. - Normally actresses don't like to play mothers. They put it off as long as they can. But for Emmy-winning actress Jean Smart, playing Christina Applegate's mom in "Samantha Who?" was a natural.

The actress known for her portrayal of the dense Charlene in "Designing Women" said family is the most important thing to her, though she's been devoted to acting since high school.

"It's difficult being away from my rest of my family, who are all in Seattle," she said. "My mother lives by herself. I worry about her. She's doing great. She lives in the house that they bought when I was 2. My sister has a serious health issue this year but she's doing good. Both my brothers are up there with their wives and kids, and I miss out a lot on family things," she said over lunch in a bistro here.

"We lost our dad six years ago to Alzheimer's, so I spend a lot of time traveling up there this last couple of years. Thank goodness I got to be with him when he passed away, which was the greatest gift I could've been given. We were all there with him," she recalled.

Married to actor Richard Gilliland, whom she met when he guest-starred on "Designing Women," and the mother of an 18-year-old son, Smart declared, "Actors shouldn't marry actors - except there isn't anybody else in the business who knows what you go through as an actor. It's the only job on the entire planet where we can never compete for the same job."

She and Gilliland separated for a year, a period which taught her what love was, she said. "I just realized how much I missed him as a friend, as a husband and comparing him to some other people that I met. He's such an incredible guy . . . Another thing that got us back together, I found out he was dating a 28-year-old school teacher, and I suddenly went, 'He's mine - you can't have him!' " she said, feigning bodily harm.

When she was just starting acting in New York she lost her first husband. "I think the first time you lose somebody you love [it] changes you forever, especially when it's a young person," she said. "It was my ex-husband. We had divorced but were still extremely close, and he died in a car accident and it just leveled me."

Smart comes from a line of determined pioneers. Her father joined the Navy at 17 to help support his family, eventually earning his master's degree and teaching history. Her grandmother was orphaned, grew up destitute but managed to earn her doctorate from Columbia. When Smart told her family she wanted to act, it was not great news.

"When I announced I was going to major in theater, my mother thought that was a bit frivolous. She changed her mind as soon as she saw me in plays at the University of Washington - which was her alma mater. They thought that was pretty great."

After college Smart eked out a living in the theater playing heavy roles like Lady Macbeth and Clytemnestra, but it was comedy that would bring her to Los Angeles and earn her rapt attention and three Emmys.

Her first sitcom was "Teachers Only" with Lynn Redgrave. She went on to do four sitcoms before she engaged tragedy again as serial killer Aileen Wuornos in "Overkill: The Aileen Wuornos Story."

Diagnosed with diabetes when she was 13, Smart was told she could never have a child. But the birth of her son, Connor, changed her life, she said.

"There's nothing like having this tiny little being depend on you, without you they won't survive. That sense of responsibility, there's something about that sense of responsibility - I guess that's what they call maternal instinct, but when you suddenly realize what they mean when they talk about that 'mother bear' thing, you realize that you could do anything almost to protect that child.

"And you would do anything to protect that child. Anything. It's so profound, changes your priorities in a really good way. I know I'm not unusual. It's not so much it changes your priorities it makes your priorities what they're supposed to be."

The new season for ABC's "Samantha Who?" began yesterday. *