McGee has been a key part of the defensive tackle rotation since 2010, compiling 17 starts over that span.
"It's a big loss," said fellow defensive tackle Casey Walker. "But we'll be all right."
McGee had informed his fellow defensive linemen in recent days that he had broken the rules and punishment might be coming. It didn't become official until Friday.
"It's one of those things where it's like, 'I knew better.' You know what I'm saying?" Walker said. "So, it's like when you're a kid and Mom tells you not to touch the stove and you do it anyway, and you got burned. It's just one of those things. He learned his lesson and whatnot, and he's just moving forward now. You can't dwell in the past."
To offset the loss of McGee, the Sooners (No. 4 USA Today) will slide starting defensive end David King to tackle. King has played tackle in spots in his career, but never full time.
"They told me today I'll be playing (defensive tackle) the first couple games of the season," King said. "I've played there before, so it's nothing new for me. I'm comfortable playing down there. I'm heavy enough to where I can play down there and hold my weight. We'll see how it goes."
Stoops said King, who filled in at tackle while McGee and Walker missed time due to injuries last season, is consistently weighing in at 275 to 280 pounds and will be able to slide inside without a problem.
"If he could treat himself to a few more cheeseburgers, he could be 285 in no time and he's got the strength to play in there. The times he has played in there, he's done well," Stoops said. "So, in all likelihood, we'll rotate him in there with those other guys."
The Sooners' season opener is Sept. 1 at UTEP.
The Sooners will also lean on Rashod Favors, who moved from outside linebacker to end during the offseason.
"Rashod Favors keeps showing up," Stoops said. "He's really strong, powerful. That's been a positive."
McGee is the third starter the Sooners have lost this preseason. Center Ben Habern elected to give up football due to lingering back and neck injuries. On the first day of practice, right guard Tyler Evans tore the ACL in his right knee.
McGee is the fifth Oklahoma player to be suspended during this offseason. Receiver Kameel Jackson was eventually dismissed from the team, while defensive back Quentin Hayes and receivers Jaz Reynolds and Trey Franks have been reinstated to practice but won't be allowed to play in games.
Information from SoonerNation's Jake Trotter and The Associated Press was used in this report.