title: Some theoretical questions of the peptide and steroid hormone regulation. Part II.: The second messenger system.
abstract: The "second messenger system" has been analysed regarding its possibilities for containing and transferring highly specific molecular, biological information. Very heterogeneous molecules were found behind the different - cyclase, diesterase, kinase,... -  activities of the system, whereas the connection realized between them by cyclic nucleotides was very poor. So, I constructed a theoretical model mostly on the basis of real and known experimental facts to resolve this obvious contradiction and make the second messenger system adequate as a highly specific biological informational channel.
mesh_terms: D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases / Q000502:physiology*; D000262:Adenylyl Cyclases / Q000502:physiology*; D000818:Animals; D001665:Binding Sites; D006162:Guanylate Cyclase / Q000502:physiology*; D006728:Hormones / Q000494:pharmacology*; D006801:Humans; D008954:Models, Biological; D009711:Nucleotides / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000502:physiology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000502:physiology*
chemical_list: D006728:Hormones; D009711:Nucleotides; D011494:Protein Kinases; D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases; D010727:Phosphoric Diester Hydrolases; D000262:Adenylyl Cyclases; D006162:Guanylate Cyclase