The Hines Interests Limited Partnership announced this week that it has sold Manhattan office buildings at 425 Lexington Avenue and 499 Park Avenue to JPMorgan Asset Management and American Realty Advisors, respectively, for a combined total of more than $1 billion, according to sibling publication GlobeSt.

Proskauer Rose and Baker Botts are taking the lead advising Hines, a Houston-based commercial real estate firm that Reuters reports will receive roughly $700 million from the sale of 425 Lexington and $390 million from the sale of 499 Park.

A spokesman for Baker Botts, which has longtime client relationship with Hines, was not immediately able to provide the names of those lawyers from the firm working on the sales.

Proskauer real estate practice cochair Ronald Sernau, dubbed one of Manhattan’s top real estate lawyers by The New York Observer in 2011, is also advising Hines, as are partner Christopher Pennington and associates Andrea Anderson and Rebecca Lesnik. Sernau did not respond to a request for comment about the deal.

Proskauer, which made a real estate splash of its own three years ago when it moved its global headquarters—and added its name—to 11 Times Square, previously advised Hines on the $485 million sale of 750 Seventh Avenue to Kuwait’s Fosterlane Management in 2011.

GlobeSt reports that Hines first put 425 Lexington and 499 Park on the market in February. GlobeSt also notes that the value of the former property—which faces Grand Central Terminal—most likely increased as a result of anchor tenant Simpson Thacher & Bartlett’s decision last month to renew its lease for 595,000 square feet of space in the building.

Simpson’s lease at 425 Lexington—where the firm occupies 26 floors of the 31-story office tower—was a key factor in the sale of the skyscraper. Simpson’s previous lease was not due to expire until 2018, meaning the 15-year renewal will keep the firm in its midtown headquarters through 2033, according to GlobeSt.

Gregory Ressa, the head of Simpson’s real estate practice in New York, was not immediately available for comment about the firm’s lease. But Hines senior managing director Thomas Craig told GlobeSt in April that with the building up for sale the firm wanted to lock in stability, something Craig said any potential buyer would want as well.

JPMorgan Asset Management, whose compliance director and assistant general counsel is Jack Cohen, turned to Debevoise & Plimpton for counsel on the deal. Leading the team from the firm working on the matter are real estate chair Peter Irwin, tax partner Peter Furci, employee benefits counsel Alicia McCarthy, real estate counsel Andrew Schultz, and associate Michael Bolotin. Debevoise advised a JPMorgan unit in 2011 on its purchase of a 90 percent stake held by Lehman Brothers in the former International Toy Center at 200 Fifth Avenue in Manhattan.

Lewis Miller, a vice-chairman at CBRE Group, led a team from the Los Angeles–based commercial real estate services giant advising both Simpson on its new lease and Hines in the marketing of 425 Lexington and 499 Park. CBRE is no stranger to large Am Law 100 firm leases, having previously advised on Wilmer Cutler Pickering Hale and Dorr’s 20-year lease for 210,000 square feet of space at 7 World Trade Center in Manhattan, according to sibling publication the New York Law Journal.

CBRE’s chief compliance officer and general counsel is Laurence Midler and the firm’s chief administrative officer is former Vinson & Elkins partner J. Christopher Kirk. Mayer Brown corporate partner and former U.S. Secretary of Commerce Michael "Mickey" Kantor is a member of CBRE’s board of directors.

Jason Maxwell, a former Locke Lord partner now serving as in-house corporate counsel for Hines in Houston, took the lead advising on the sale of both buildings by the privately owned company. Profiles of the two properties posted on Hines’s website show that other key tenants at 425 Lexington include the Canadian Imperial Bank and FleetBank. The 28-story 499 Park, designed by architect I.M. Pei, is the former headquarters for Bloomberg LP. The building’s current tenants include Hines and financial services firm Cantor Fitzgerald.

A quartet of attorneys working for 499 Park’s buyer American Realty Advisors—chairman Stanley Iezman, president Scott Darling, COO Scott Kurzban, and chief legal and compliance officer Kristin Adrian—did not respond to requests for comment about the Glendale, California–based real estate investment management firm’s legal advisers. Adrian is a former partner at San Francisco’s Bronson, Bronson & McKinnon, which closed its doors in 1999.

The Am Law Daily has previously reported that office leases trail only personnel-related costs on the expense ledgers of most Am Law 100 firms. And as many large firms look to trim real estate spending by locking in lower-cost leases as the economy continues to sputter, some commercial landlords are losing key tenants and, in turn, putting office buildings up for sale.

One property owner stuck in this bind is Manulife Financial Corp., a Toronto-based holding company for The Manufacturers Life Insurance Company and John Hancock Financial Services, which is seeking buyers for the Thurman Arnold Building in Washington, D.C., as a result of the looming departure of anchor tenant Arnold & Porter, according to a report this month by the Washington Business Journal. (Arnold & Porter founding partner Thurman Arnold led the U.S. Department of Justice’s antitrust division under President Franklin Delano Roosevelt.)

Arnold & Porter is set to vacate the 12-story property in 2015 for new office space being built for the firm by real estate investment trust Boston Properties on the site of the former headquarters of National Public Radio. The latter building is being razed to make way for a new development with 478,000 square feet of space that Boston Properties has said is already 79 percent leased. Arnold & Porter has signed a 20-year lease, according to sibling publication The Blog of Legal Times.

Jean-Paul Bisnaire, a former senior corporate partner at leading Canadian firm Davies Ward Phillips & Vineberg and now general counsel for Manulife, did not immediately respond to a request for comment on the names of any outside legal advisers retained for the proposed sale of the Thurman Arnold Building.

As for Proskauer, the firm teamed up this week with Canadian shop Heenan Blaikie and U.K. firm Pinsent Masons to advise London-based building products company Tyman on its $200 million acquisition of Owatonna, Minnesota–based building products manufacturer Truth Hardware, according to British publication Legal Week. Truth Hardware, a unit of London-based investment firm Melrose Industries, will be absorbed into Tyman’s U.S. unit Amesbury Group. Simpson counseled Melrose on the deal.

Additional reporting by Sara Randazzo.