A joint venture of The Davis Cos. and Marcus Partners has sold a 515K SF office and life sciences complex in Waltham with further development potential for $330M.

Included in the deal is an additional 440K SF of as-of-right developable life sciences space, according to a release from Newmark Knight Frank, which represented the seller and found the buyer. Alexandria Real Estate Equities, one of the largest life sciences developers in Greater Boston and the country, bought the property, Banker and Tradesman reports.

Reservoir Woods East consists of a three-story, nearly 313K SF office building at 40 Sylvan Road and two lab buildings at 50-60 Sylvan Road totaling more than 202K SF. Electric and gas utility National Grid has a long-term lease at 40 Sylvan Road, which serves as its U.S. headquarters. A subsidiary of Verizon Laboratories has a short-term lease at 50-60 Sylvan Road.

Alexandria listed a pending $330M Boston-area purchase on a Securities and Exchange Commission filing last month, disclosing that the two-parcel site has 400K SF of future development, 200K SF of operating space with future redevelopment potential and 300K SF of operating space.

The REIT owns 7.6M SF of Boston-area commercial properties with an annual estimated rental revenue of $475M, it said in the filing.

Demand for life sciences space is booming, especially in the Boston area. In the last month, Bristol Myers Squibb signed a new lease for 360K SF in Cambridge, and CRISPR Therapeutics signed on for 264K SF at a Tishman Speyer joint venture-developed spec building in Boston that is more than a year away from delivery.

Waltham has seen surging life sciences activity along Route 128. Deciphera Pharmaceuticals moved its headquarters to the suburb last spring, and a four-story, 140K SF development was approved last summer.

“Reservoir Woods East offers an attractive combination of near-term cash flow and long-term development upside within Greater Boston, which is arguably the country’s most attractive market,” NKF Boston Capital Markets Group Vice Chairman Edward Maher said in the release. “The property presents an exceptional opportunity to benefit from the momentum of the Waltham-Lexington life science cluster, which has become a bona fide extension of Cambridge in recent years.”

NKF co-Head of U.S. Capital Markets Robert Griffin, Boston Capital Markets Group Executive Managing Director Matthew Pullen and Managing Director Samantha Hallowell joined Maher in brokering the sale, which includes a 410-space parking structure.