Actin capping proteins belong to the core set of proteins minimally required for actin-based motility and are present in virtually all eukaryotic cells. They bind to the fast-growing barbed end of an actin filament, preventing addition and loss of monomers, thus restricting growth to the slow-growing pointed end. Actin capping proteins are usually heterodimers of two subunits. The Plasmodium orthologs are an exception, as their a subunits are able to form homodimers. We show here that, while the beta subunit alone is unstable, the alpha subunit of the Plasmodium actin capping protein forms functional homo- and heterodimers. This implies independent functions for the alpha alpha homo- and alpha beta heterodimers in certain stages of the parasite life cycle. Structurally, the homodimers resemble canonical alpha beta heterodimers, although certain rearrangements at the interface must be required. Both homo- and heterodimers bind to actin filaments in a roughly equimolar ratio, indicating they may also bind other sites than barbed ends. (C) 2020 Published by Elsevier Inc.