title: Interaction of vitamin K dependent proteins with membranes.
abstract: The membrane-binding characteristics of six vitamin K dependent plasma proteins, which have homologous amino acid sequences, were compared. All of these proteins display calcium-dependent membrane binding and the identified equilibria for protein-membrane binding are qualitatively the same for all proteins. Quantitative characteristics of these protein-membrane interactions allow organization into distinct subgroups. Protein C and factor VII form a subgroup which has extemely low affinity for bilayer membranes; prothrombin, factor X, and protein S form the tightest complexes with membranes and factor IX displays intermediate affinity. In the presence of manganese (which substitutes for calcium in a cation-dependent protein transition), calcium titration of protein-membrane binding shows the same calcium dependence for all proteins except prothrombin which requires lower calcium. These protein-membrane binding characteristics agree very well with the relatedness of these proteins based on their partial amino-terminal sequences.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D001798:Blood Proteins; D002118:Calcium; D002642:Chick Embryo; D005164:Factor IX; D005170:Factor X; D006801:Humans; D007700:Kinetics; D008567:Membranes, Artificial; D011485:Protein Binding; D014812:Vitamin K
chemical_list: D001798:Blood Proteins; D008567:Membranes, Artificial; D014812:Vitamin K; D005164:Factor IX; D005170:Factor X; D002118:Calcium