Public relations powerhouse Prosek Partners has acquired Westwood-based Muirfield Partners for an undisclosed amount of cash and equity from Muirfield founder Mickey Mandelbaum.

The 10-person financial communications boutique founded by Mandelbaum in 2001 will be absorbed by New York’s Prosek. The addition brings the firm’s headcount to 135 and establishes a West Coast base of operations for the agency.

“Prosek has grown its West Coast client base substantially over the past several years,” said the firm’s managing partner Jen Prosek in a statement. “With the acquisition of Muirfield we not only establish a physical presence there, we also add to and strengthen our existing capabilities.”

Mandelbaum, who will become a partner at Prosek, primarily handles communications work on behalf of financial institutions including downtown’s TCW Group Inc. While this is the first time he’s sold a company, Mandelbaum said he expects the transition to be smooth despite going from a boutique atmosphere to a larger corporate environment.

“Any partnership like this stands a much greater chance to work if there a good cultural fit and everyone works well together, which we feel is the case,” he said.