SAN JOSE — One of downtown San Jose’s iconic office towers, a high rise crowned by a KQED sign, has been bought by prolific Bay Area developer Jay Paul Co. in a deal that points to robust interest in the urban heart of the Bay Area’s largest city.

Jay Paul, a veteran development firm that has achieved spectacular success with tech campuses in Sunnyvale and a mixed-use residential and office tower in San Francisco, has struck a deal to purchase the 50 W. San Fernando high rise, according to several experts familiar with the Silicon Valley property market.

The 18-story tower totals 357,000 square feet and is currently owned by a venture of DivcoWest, a real estate investment firm, and Rockpoint Group, a real estate private equity company.

The tower is being bought for $230 million, according to sources familiar with the South Bay property market. As of Monday evening, the property transfer had not been formally filed with the Santa Clara County Recorder’s Office.

The building was constructed in 1989 by Kimball Small, one of the first developers to be active in downtown San Jose. KQED is one of the tower’s tenants.

“It’s an iconic asset that makes total sense for Jay Paul’s portfolio in downtown San Jose,” said Phil Mahoney, an executive vice chairman with Newmark Knight Frank, a commercial real estate firm.

Jay Paul’s tenant list reads like a who’s who of several of the world’s greatest companies — Google, Amazon, and Facebook are among the clients that lease vast stretches of office space from the developer in the Bay Area.

Now, the development stalwart has embarked on what appears to be the creation of a dramatically widening portfolio of office sites and buildings in downtown San Jose.

The combined value of Jay Paul’s downtown San Jose investments has reached a head-spinning $560 million, including the anticipated $230 million price tag reported by sources for the 50 West tower. Jay Paul Co. didn’t comment about the 50 West transaction.

In July 2018, a Jay Paul affiliate paid $283.5 million in cash for nearly all of CityView Plaza, a 580,000-square-foot complex of offices, shops, and restaurants that is bounded by West San Fernando Street, South Almaden Boulevard, Park Avenue and South Market Street.

Weeks later, in August 2018, a Jay Paul group bought a historic office building that once was a JC Penney department store at North First and West Santa Clara streets, paying $46 million for the 120,000-square-foot structure, in a deal arranged by Cushman & Wakefield broker Erik Hallgrimson.

The Jay Paul activity arrives as two major tech companies, Adobe and Google, have launched wide-ranging efforts to dramatically increase their respective footprints in downtown San Jose.

San Jose-based Adobe will expand its downtown headquarters campus that now consists of three office high rises by constructing a fourth office tower on an adjacent lot where 4,000 of the cloud services titan’s employees would work.

Near the Diridon train station and SAP Center, Mountain View-based Google has proposed a transit-oriented community of office buildings, homes, restaurants, shops and open spaces where 25,000 people could work, including 15,000 to 20,000 of the search giant’s workers.

“While there is a Google bounce on real estate, there is a Jay Paul bounce on the office market downtown,” said Bob Staedler, principal executive with Silicon Valley Synergy, a land use consultancy.

50 West now features a KQED sign at its roofline and its upper floor is home to Silicon Valley Capital Club, a private dining and events center that commands eye-popping views of San Jose and the Santa Clara Valley.

DivcoWest and Rockpoint in recent months launched a quest to increase the prior capacity of the building by converting the top floor of the tower into a space for office tenants, hoping to eventually add 14,000 square feet.

“It’s heartening that a major city like San Jose continues to draw major investors like Jay Paul,” said Carl Guardino, president of the Silicon Valley Leadership Group, a business group. “Jay Paul not only does quality work, but they are based locally, and part of the fabric of our region.”