Binds to F-actin in a calcium-independent manner. Has no direct effect on actin depolymerization. Acts as a chaperone for ALOX5 (5LO), influencing both its stability and activity in leukotrienes synthesis. Interacts with 5-lipoxygenase (ALOX5/5LO) in a calcium-independent manner. Binds to F-actin with a stoichiometry of 1:2. Widely expressed with highest levels in placenta, lung, kidney and peripheral blood leukocytes and lower levels in brain, liver and pancreas. Belongs to the actin-binding proteins ADF family. Coactosin subfamily.