Opus Bank, based in Irvine and with $2.4 billion in total assets, expanded its branches in San Diego County by three after it completed the acquisition of 10 branches formerly belonging to PacWest Bancorp.

The three new branches are in Carlsbad, El Cajon and La Mesa, and bring Opus’ presence in the county to five branches. The remaining seven branches are in Los Angeles, Riverside and San Bernardino counties.

Opus said it purchased $125 million in deposits and cash, and property associated with two of the 10 locations, but no loans. It’s paying a 2.5 percent premium on the money or about $3 million.

In earlier announcements on the transaction, both banks said the acquisition involved $143 million in deposits at the 10 branches.

PacWest, based in Los Angeles and with $5.3 billion in assets, estimated the annual cost savings from the transaction at $2 million.