There are at least two protein isoforms of the Double C2 protein, namely alpha (DOC2A) and beta (DOC2B), which contain two C2-like domains. DOC2A and DOC2B are encoded by different genes; these genes are at times confused with the unrelated DAB2 gene which was initially named DOC-2. DOC2B is expressed ubiquitously and is suggested to be involved in Ca(2+)-dependent intracellular vesicle trafficking in various types of cells.