A corporate cousin to Georgia-Pacific has bought an interest in the paper product company’s well-known red granite headquarters in downtown Atlanta.

The transaction, Georgia-Pacific said in a news release Thursday, signifies the company’s commitment to downtown. Georgia-Pacific been based at the stair-stepped building at 133 Peachtree Street NE in Woodruff Park since it opened in 1982.

The 51-story tower houses many corporate tenants, but Georgia-Pacific is the largest, with more than 2,500 employees based there, the company said.

The property was jointly owned with insurance giant MetLife. Now an affiliate company of Georgia-Pacific parent Koch Industries controls the former MetLife share. A price was not disclosed.