There are at least two types of sorting signals on proteins One type resides in a continuous stretch of amino acid sequence(a single stretch, or bipartite), called as signal peptides or presequences (targeting sequences, leading peptides) used to direct moving to ER, Nucleus, Mit, ChI etc typically 15 to 60 residues long for ER. These signal peptides are usually removed from finished protein by a specialized signal peptidase once the sorting process has been completed Some other: signal peptides (internal topogenic sequence) retain in the acrossed membrane to be the membranous parts of integrated protein in certain organelles. The other type consists of a specific three-dimensional arrangement of atoms on the folded, even sugar residue-marked proteins surface, called as signal patch to bind to a matched three-dimensional domain or motif of a receptor in the appropriate membrane of certain organelles. Such as M6-P marked lysosomal enzymes move from gC to lysosomesThere are at least two types of sorting signals on proteins. One type resides in a continuous stretch of amino acid sequence (a single stretch, or bipartite), called as signal peptides or presequences (targeting sequences, leading peptides) used to direct moving to ER, Nucleus, Mit, Chl etc., typically 15 to 60 residues long for ER. These signal peptides are usually removed from finished protein by a specialized signal peptidase once the sorting process has been completed. Some other signal peptides (internal topogenic sequence) retain in the acrossed membrane to be the membranous parts of integrated protein in certain organelles. The other type consists of a specific three-dimensional arrangement of atoms on the folded, even sugar residue-marked protein’s surface, called as signal patch to bind to a matched three-dimensional domain or motif of a receptor in the appropriate membrane of certain organelles. Such as M6-P marked lysosomal enzymes move from GC to lysosomes