title: Presence of the epsilon-(gamma-glutamic)lysine crosslink in cellular proteins.
abstract: The epsilon-(gamma-glutamic)lysine bond is a covalent interaction which has been found to crosslink polypeptide chains of a number of extracellular proteins. Among known covalent bonds crosslinking protein chains, it is unique in that it is formed directly by enzymatic catalysis, a property which may also endow Glu-Lys crosslink formation with important intracellular functions. We found glutamic-lysine bonds to be present in the procaryote, Escherichia coli, in primitive eucaryotes such as the slime mold, Physarum polycephalum, and the ciliate, Paramecium aurelia, and in muscle cells of a bird and a mammal. Our data show that, although Glu-Lys bonds occur in low concentrations in cellular proteins, they are nevertheless widely distributed. Evidence is also presented indicating that the low levels of the Glu-Lys bonds we measure in the proteins of various cells types are not artifacts of our analytical procedures.
mesh_terms: D000818:Animals; D005971:Glutamates; D008239:Lysine; D046911:Macromolecular Substances; D011485:Protein Binding; D011506:Proteins; D013045:Species Specificity
chemical_list: D005971:Glutamates; D046911:Macromolecular Substances; D011506:Proteins; D008239:Lysine