Even a seasoned comedy veteran like Jane Curtin admits it’s often difficult to keep a straight face on NBC’s hit sitcom “3rd Rock From the Sun.”

“When it comes to the actual doing of the show, we try desperately to make sure we are professional,” says Curtin, who came to fame in 1975 as one of the original Not Ready for Prime Time Players on “Saturday Night Live” and then starred for five years in the sitcom “Kate & Allie.”

“But,” she adds, “there have been a couple of times when it has been to our benefit to break up.’


Like the time when John Lithgow’s gooney alien character, Dick Solomon, was strutting around like a peacock in skin-tight, black leather pants that squeaked.

“It would have been impossible to do that scene had I not been allowed to break up,” Curtin, 49, explains. “There have been times when John and I have been doubled over on the floor over the things that we do.”

In fact, Curtin says, “my sister wants to make these terry cloth mittens that I can wear during rehearsals so I can have an absorbent mitt, because I have the tendency to cry when I laugh.”

In “3rd Rock,” Curtin plays the straight-laced, sarcastic college professor, Mary Albright, who shares her office with physics professor Solomon. Dick is actually the high commander of an alien expedition sent to Earth to study its inhabitants.

After spurning his fervid romantic advances most of last season, Mary has finally succumbed to Dick’s puppy dog charms. Curtin believes Mary could have held out a little longer before linking up with Dick.

“My daughter is convinced we are going to end up like Ross and Rachel [on “Friends”],” she says, laughing. “I don’t think that will happen.”

Part of the fun of “3rd Rock” is that, on the surface, both Lithgow and Curtin look far too dignified and sophisticated to be playing such goofs.

“It’s much more fun to see proper people make fools of themselves,” Curtin offers, “than it is to see idiots make fools of themselves.

In recent episodes, audiences have learned that Mary was actually a musical theater major in college and was once so fat that she had to give up her parents’ dream of becoming a championship ice skater.

Curtin relishes being a clown. “I love this so much,” she says.

The actress, who is as funny in real life as she is in reel life, is sitting in the audience section of the Studio City sound stage of “3rd Rock.” The crew is busy dismantling the set from the previous evening’s taping. Casually dressed in blue jeans and a sweatshirt, Curtin has just finished a table reading of an upcoming episode in which dimwitted alien Harry (French Stewart) runs for city council.

“I don’t know anybody that has ever been on this show who doesn’t love it so much,” she says. “There’s not one person who doesn’t get to do something that either they have always wanted to do or has always wanted to be put in that position where you can just sort of be stupid.”

Curtin didn’t even care what “3rd Rock” was about initially; she was just eager to work again with creators and executive producers Terry and Bonnie Turner.

“They did ‘The Coneheads’ [movie],” she says, referring to the 1993 film in which she, Dan Aykroyd and Laraine Newman re-created their popular “Saturday Night Live” characters. “Bonnie was my saving grace. She kept me company while I was sitting on the set in the director’s chair with a cone on my head. She would have serious conversations with me about kids and I had the cone on my head. I just loved them.”

But doing the series meant that Curtin; her husband Patrick Lynch, a producer; and 13-year-old daughter Tess had to relocate to Los Angeles.

“I am here for the duration of the show,” Curtin says. “When the show is over I can go back to Connecticut.”

Curtin, who has appeared on Broadway (“Candida”), starred in feature films (“How to Beat the High Cost of Living”), TV movies (“Divorce Wars--A Love Story”) and miniseries (“Common Ground”), says the sitcom is her favorite format.

“I had tried everything. I kept looking for the perfect forum for the perfect job. This is the most fun. I like instant gratification. You get to do a show in front of an audience and in front of a camera and then forget it and go on. Next week you have a whole different play to produce.”

The actress won two Emmy Awards for her sparkling performance as the old-fashioned, sweet, divorced mom Allie Lowell in the 1984-89 CBS sitcom, “Kate & Allie,” which also starred Susan St. James.

“Kate & Allie,” she says, had a lot of heart. “It had a wonderful sense of humor. Overall, it was done very, very well and the character was so much fun to play. I had a ball doing it.”

Curtin also had a ball doing “SNL” along with Chevy Chase, John Belushi, Gilda Radner, Bill Murray, Garrett Morris, Aykroyd and Newman.

“It was the ‘70s and ‘80s, which was just a ridiculous period where people were tremendously self-indulgent and behavior was reprehensible,” she says. “But the 90 minutes of the show were the most exciting thing you could ever imagine. There were so many elements that just came bombarding you 10 minutes before the show started, and then you were shot out of the cannon.”

During her five seasons on “SNL,” Curtin played such memorable characters as the caustic “Update” anchor, the sweet, slovenly Mrs. Loopner (mother of Lisa), and the matriarch of the Conehead alien clan from the planet Remulak.

“I hated doing the Coneheads because of the glue,” Curtin says with a shudder. “The glue was just horrible. I liked Mrs. Loopner the best because I got to wear a house coat and big fluffy slippers.”

“3rd Rock From the Sun” airs Sundays at 8 p.m. on NBC.