Cultural institutions in Los Angeles sometimes bemoan the difficulty of cultivating generous donors who will help fund their operations. Over the last few years, the art collector Jarl Mohn, 72, has emerged as an exception.

He and his wife, Pamela, 71, recently gave 260 works from their collection of Los Angeles artists to be shared by three museums — Los Angeles County Museum of Art (LACMA), the Hammer Museum and the Museum of Contemporary Art, Los Angeles (MOCA). The gift also came with a $15 million to $20 million endowment for new acquisitions and expenses, in part so that works can travel to museums in other cities.