Miscellaneous human protein groups. The five boxes represent functional classes of proteins that do not fit within the definition of receptors, enzymes, or transporters. Structure/Adhesion proteins are those that build up structure between or within cells or mediate adhesion between the cell and the surroundings. Ligand proteins are groups that mainly function as ligands, structures that bind to receptors. Vesicle membrane proteins are proteins found in the membrane of cellular vesicles. The large Other group are protein groups of various functions that do not fit together with the other groups. Proteins of 'unknown function' show groups of related proteins for which no known function has been found. The number of genes and their function for each group have been determined by combining results from clustering, using the ISODATA algorithm, with data from the literature and public databases. Primarily HGNC and UniProt were used. Consensus TM helix numbers have been set through evaluation of data from external resources among the literature and databases together with prediction results from Phobius, SOSUI, and TMHMM.