Golden Gate University, which made it known last year that it is using only a fraction of its main campus building at 536 Mission Street and was seeking a buyer so that it can downsize somewhere, appears to have found that buyer.

The deal isn't completely settled, but things are moving forward and a Texas-based developer, Lincoln Property Company — which already manages the nearby Salesforce Transit Center — has submitted two optional plans to the city for constructing a tall tower at 536 Mission. One plan features a 700-foot (46-story) office tower with 1.3 million square feet of office space. And the other, as the Chronicle reports today, would be a 650-foot tower with about half of it devoted to offices, and the other half being 370 residential units.

Lincoln Property confirmed in June that it had entered a "strategic partnership" with the financially troubled Golden Gate University, offering the school a $21.9 million loan to cover its existing debts on its campus property, and taking out an option to purchase the property outright in the coming years. That sale appears to be contingent on what the developer concludes it can build there — and, obviously, whether they think it will be profitable.

San Francisco-based architecture firm SOM (formerly Skidmore Owings and Merrill) is listed as the project architect in an application for redevelopment, as the Chronicle reports. And the developer and the university issued a joint statement saying that the application is "the next step forward in our strategic partnership to enhance the long-term value of Golden Gate University’s main campus."

They say they are seeking dual entitlements for the two different project options "allowing us the flexibility to respond thoughtfully to market dynamics while maximizing the site’s potential to serve both the university and the surrounding community."

If the mixed-use option ends up being chosen down the road, it would still be a 46-story tower, and would feature 160 one-bedroom units, 100 two-bedroom units, and 110 studios.

Whether the tower is 100% office or 50% office, it's still a pretty good sign that another developer is talking about building offices in San Francisco, given that about a third of SF office space is still sitting empty. This is the second proposal for a new office tower in just a month's time. In early July, we learned that developer Hines is looking to build a tower even taller than Salesforce Tower, 1,225 feet, at 77 Beale Street. That building, which would be the tallest building west of the Mississippi if gets built, would include 1.6 million square feet of new office space.