FYVE domain like superfamilyFYVE domain is a 60-80 residue double zinc finger motif-containing module named after the four proteins, Fab1, YOTB, Vac1, and EEA1. The canonical FYVE domains are distinguished from other zinc fingers by three signature sequences: an N-terminal WxxD motif (x for any residue), the central basic R(R/K)HHCRxCG patch, and a C-terminal RVC motif, which form a compact phosphatidylinositol 3-phosphate (PtdIns3P, also termed PI3P)-binding site. They are found in many membrane trafficking regulators, including EEA1, Hrs, Vac1p, Vps27p, and FENS-1, which locate to early endosomes, specifically bind PtdIns3P, and play important roles in vesicular traffic and in signal transduction. Some proteins, such as rabphilin-3A and alpha-Rab3-interacting molecules (RIMs), are also involved in membrane trafficking and bind to members of the Rab subfamily of GTP hydrolases. However, they contain FYVE-related domains that are structurally similar to the canonical FYVE domains but lack the three signature sequences. At this point, they may not bind to phosphoinositides. In addition, this superfamily also contains the third group of proteins, caspase-associated ring proteins CARP1 and CARP2. They do not localize to membranes in the cell and are involved in the negative regulation of apoptosis, specifically targeting two initiator caspases, caspase 8 and caspase 10, which are distinguished from other FYVE-type proteins. Moreover, these proteins have an altered sequence in the basic ligand binding patch and lack the WxxD motif that is conserved only in phosphoinositide binding FYVE domains. Thus they constitute a family of unique FYVE-type domains called FYVE-like domains. The FYVE domain is structurally similar to the RING domain and the PHD finger. This superfamily also includes ADDz zinc finger domain, which is a PHD-like zinc finger motif that contains two parts, a C2-C2 and a PHD-like zinc finger.