title: Structure and evolution of calcium-modulated proteins.
abstract: This review suggests that the intracellular functions of calcium are best understood in terms of calcium's functioning as a second messenger. Further, when functioning as a second messenger, calcium completes its mission not by transferring charge nor by binding to lipid but by binding to specific targets, calcium-modulated proteins. This concept is broadly interpreted to include proteins involved in calcium transport. There is strong evidence that many, if not all, of these calcium-modulated proteins are homologs. Their structures and properties are contrasted to those of extracellular calcium-binding proteins which are not homologous to one another or to the intracellular calcium-modulated proteins. Finally, this line of thought leads to a suggestion of the evolutionary reason for the choice of calcium as the sole inorganic second messenger.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000227:Adenine Nucleotides / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D000331:Aequorin / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D017310:Annexin A7; D005075:Biological Evolution; D002135:Calcium-Binding Proteins / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002147:Calmodulin / Q000502:physiology; D003285:Contractile Proteins / Q000378:metabolism; D011756:Diphosphates / Q000378:metabolism; D049454:Firefly Luciferin / Q000494:pharmacology; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007448:Invertebrates / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D009218:Myosins / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D010764:Phosphorylase Kinase / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000378:metabolism; D015800:Protozoan Proteins; D012519:Sarcoplasmic Reticulum / Q000201:enzymology; D013379:Substrate Specificity; D014336:Troponin / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D000227:Adenine Nucleotides; D017310:Annexin A7; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D003285:Contractile Proteins; D011756:Diphosphates; D010320:Parvalbumins; D011506:Proteins; D015800:Protozoan Proteins; D014336:Troponin; D014404:Tubulin; C026555:spasmin; D000331:Aequorin; D049454:Firefly Luciferin; D014446:Tyrosine 3-Monooxygenase; D010764:Phosphorylase Kinase; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D010447:Peptide Hydrolases; D009218:Myosins; D000262:Adenylyl Cyclases; D000252:Calcium-Transporting ATPases; D008274:Magnesium