LPXTG motif (where X can be any amino acid), then transfers the protein onto the cell wall. Several analogous systems are found that likewise feature a signature motif on the extra-cytoplasmic face, a C-terminal transmembrane domain, and cluster of basic residues on the cytosolic face at the protein's extreme C-terminus. The PEP-CTERM/exosortase system, found in many Gram-negative bacteria, seems to be related to extracellular polymeric substance production. The PGF-CTERM/archaeosortase A system in archaea is related to S-layer production. The GlyGly-CTERM/rhombosortase system, found in the Shewanella, Vibrio, and a few other genera, seems involved in the release of proteases, nucleases, and other enzymes. Bioinformatic tools Minimotif Miner is a bioinformatics tool that searches protein sequence queries for a known protein targeting sequence motifs. Phobius predicts signal peptides based on a supplied primary sequence. SignalP predicts signal peptide cleavage sites. LOCtree predicts the subcellular localization of proteins. See also Bulk flow COPI COPII Clathrin LocDB PSORTdb Signal peptide References External links Post-translational modification Membrane proteins