Jackson has taken his place in the starting lineup at split end during the opening days of training camp this week after missing all of the team's spring drills with a lingering toe injury.

He is gradually getting comfortable in an offense that features new responsibilities, but it already has become apparent to those around Jackson the difference he can make at what has been one of San Francisco's weakest positions.

"Darrell brings that veteranship, a guy that has been there, done that, has been to the playoffs, has had big seasons, who's caught the big catches in the clutch situations and knows what it takes," said Arnaz Battle, who emerged last season as the 49ers' leading receiver among wideouts with a career-high 59 receptions. "He's a guy that's going to help us out tremendously."

Jackson did all those things previously in his career with the Seattle Seahawks, who traded the eighth-year veteran to the division-rival 49ers on April 29 for a fourth-round draft pick. Jackson started all seven seasons he played in Seattle and led the Seahawks in receiving four of the past six years.

Now he slides into the featured No. 1 role in San Francisco that he filled in for in Seattle.

The 49ers haven't had a receiver with Jackson's credentials since All-Pro Terrell Owens left town after the 2003 season. The 49ers haven't got more than 48 receptions in a season from their starting split end since then, and both Brandon Lloyd and Antonio Bryant quickly wore out their welcome in San Francisco with their attitude and behavior.

Jackson is just looking to fit in with a revamped offense, and he has displayed early in camp the smooth route-running and ability to get open that have been trademarks of his game.

"I want to be a big part of this offense and a big part of the success we're going to have this year," Jackson said. "It's a more vertical offense than I was in at Seattle, but I definitely think I can be as productive in this. My job is just to get open, and I will be open."

Jackson is running longer routes downfield and deeper crossing patterns than he was accustomed to in Seattle, where he often took quick timing passes and did his damage running after the catch. Jackson averaged 15.2 yards on his 63 receptions last season and was leading the NFL with 10 touchdown receptions in December before a turf toe condition forced him out of the lineup.

Jackson averaged 63 receptions, 921 receiving yards, a 14.6 average and seven touchdowns a season in Seattle, and the 49ers envision him providing a big boost to a passing attack that ranked 29th in the league last season.