After more than a year of searching for a suitor, California Pizza Kitchen Inc. on Wednesday said it had reached a definitive agreement with an affiliate of Golden Gate Capital to be acquired for about $470 million in cash.

The $18.50 per share price that Golden Gate agreed to pay is a nearly 11 percent premium to the Los Angeles restaurant chain’s closing price on Tuesday. San Francisco-based Golden Gate is a private equity firm that owns or has significant stakes in several restaurant and retail chains, including On the Border Mexican Grill & Cantina and Romano’s Macaroni Grill.

“Golden Gate Capital is a leading investor in the restaurant industry, with a proven track record as a value-added partner to its portfolio companies, and we believe that its significant commitment and experience in the sector will benefit all of our stakeholders,” co-chief executives Rick Rosenfield and Larry Flax said in a statement.

California Pizza Kitchen has more than 250 locations in 32 states and several foreign countries. It and other casual chains have been facing rising food costs at the same time they continue to deal with fewer diners or customers who order less when they do eat out. The company has been working to cut costs and increase margins by eliminating low-selling and low-margin dishes from its menu.

The deal calls for the Golden Gate affiliate to commence a tender offer to pay cash for all of the outstanding shares no later than June 8. The company said it expects the deal to close in the third quarter.

Several law firms already have announced investigations into whether the acquisition was a good deal for shareholders. The company emphasized in its announcement that the offering price represented a 15 percent premium to the 30-day average price prior to today, and a 32 percent premium to its 30-day average price prior to the board authorizing management to explore strategic alternatives on Feb. 23, 2010.

Shares closed up $1.76, or 10.5 percent, to $18.47 on the Nasdaq.