Penta-EF-hand domain containing 1, also known as PEF1, belongs to the penta-EF-hand protein family, which shares similarities to the apoptosis linked gene ALG-2. PEF1 heterodimerizes with PDCD6/ALG2 and dissociates from PDCD6/ALG2 in the presence of Ca (2+). Also, PEF1 proteins bind calcium and participate in a variety of calcium-dependent processes in vertebrates.