Nick Collison has called time on his 15-year NBA career.

The 37-year-old native of Orange City, IA made the announcement in a special ESPN column.

Collison's entire career was spent with only one organization - the Seattle SuperSonics/Oklahoma City Thunder.

"I've played with some incredible players, future Hall of Famers, and had the unique experience of spending my entire career with one franchise, but in two different cities," Collison wrote. "I started in cold gyms in small towns in Iowa and ended up playing in more than 1,000 games over 15 years in the best league in the world. I've had an incredible run. I'm proud of my career."

Taken with the 12th overall pick of the 2003 NBA Draft out of Kansas, Collison is one of only eight players from his draft class to play in the NBA this season with the octet playing on only three different clubs. Four of the other seven played for the Cleveland Cavaliers in LeBron James (first overall), Dwyane Wade (third overall, later traded to the Miami Heat), Kendrick Perkins (27th overall) and Kyle Korver (51st overall), while David West (18th overall) and Zaza Pachulia (42nd overall) played for the Golden State Warriors. The final player is Collison's Thunder teammate, Carmelo Anthony (second overall).

Collison appeared in only 15 games this season and 20 in the year before, so thoughts of retirement had been on his mind for the past several seasons.

Collison says he treasured his time in Oklahoma City.

"I've been in OKC 10 years now, and the fans have been incredible," he wrote. "They are there every night; they know the game and appreciate effort. From day one we felt the love, and I want everyone to know I've loved playing in Oklahoma City. It's always meant so much to me and my family that the people of Oklahoma City appreciated what I did. Most people don't get to feel anything like that. I've had it for 10 years and I am grateful."

But he also expressed disappointment that basketball fans in Seattle are now without a team.

"I learned an important lesson: The NBA is a business and all the parties involved will always act in their own best interests," Collison wrote of the move in 2008. "The fans in Seattle deserved better, and I hope they get a team back someday soon."

In 910 career games over 15 seasons, Collison averaged 5.9 points, 5.2 assists and 1.0 assists a night. His career-best year came in 2007-2008, the final year of the Sonics' existence, when he nearly averaged a double-double with 9.8 points and 9.4 boards a night.