ATLANTA -- Lacking the kind of size typically necessary to successfully play the 3-4 front, the Atlanta Falcons addressed that shortcoming Sunday by signing former Indianapolis Colts defensive tackle Ellis Johnson, ESPN.com has learned.

The Falcons also acquired third-year wide receiver Trevor Gaylor in a trade, sending an undisclosed choice in the 2004 draft to the San Diego Chargers for the former Miami of Ohio star. To reach the mandatory 53-player roster limit, Atlanta released wide receiver Quentin McCord, fullback George Layne and cornerback Darrick Vaughn.

A seven-year veteran and the Colts' first-round choice in the 1995 draft, Johnson was jettisoned last week after he approached Indianapolis officials and asked to be released. He said he felt he did not fit well into the one-gap scheme implemented by new coach Tony Dungy and coordinator Ron Meeks, and preferred more playing time.

Johnson, 28, signed a three-year contract worth $4.5 million, with a signing bonus of $1 million and a base salary of $650,000 for 2002. There were a number of other teams interested in Johnson, but some offered just one-year contracts, and others simply did not appeal to him as much as the situation with the new-look Falcons defense.

The Colts left the door open for his return, telling Johnson he could return if he didn't find work elsewhere, but he seemed determined to find a new home.

The former University of Florida standout, who weighs about 288 pounds, has the kind of size the Falcons have lacked upfront as they convert to the 3-4 front under Wade Phillips, their coordinator in his first year with the club. Although he will play some at tackle, spelling starter Ed Jasper there, it's expected Johnson will line up primarily at end.

A lingering abdominal injury that has kept Travis Hall off the field for the entire preseason and a shoulder injury that will sideline Shane Dronett the entire year has left the Falcons without size at defensive end. Phillips has stressed the importance of speed in the 3-4, but opponents have been able to run on Atlanta in the preseason, and the front is difficult to play without bigger ends.

The addition of Johnson, a stalwart in his seven years with the Colts, might allow Patrick Kerney to move to right end in pass-rush situations. Kerney had 12 sacks for the Falcons in 2001. Certainly the acquisition just further upgrades a unit that underachieved last year, when it ranked No. 30 in the NFL, but which should be much improved this season.

Johnson already was in Atlanta on Sunday and is expected to begin practice with the Falcons on Monday, and probably will play in the opener Sunday at Green Bay. He visited with Falcons officials Friday and, despite thinking about a few other options, clearly liked what he saw and heard.

He has 271 tackles, 33 sacks, four forced fumbles, two interceptions and 20 pass deflections in his career, which includes 104 appearances and 84 starts. Over the past five seasons, Johnson averaged 15.2 starts. His best season was in 1998 when he registered 55 tackles and eight sacks.

In Gaylor, the Falcons are getting a big, physical wide receiver who did not live up to his billing with the Chargers, but who might benefit from a change of scenery. Given the team's need for a young deep threat, the deal could turn out to be a good one for the Falcons.

A fourth-round choice in the 2000 draft, Gaylor, 24, has played in 21 games and started five contests. He has 27 catches for 399 yards and one touchdown.

Len Pasquarelli is a senior writer for ESPN.com.