[Origin and evolution of peptide-protein bioregulators].

Possible evolutionary pathways of cellular regulatory systems are discussed. Analysis of animal evolution suggests that peptide and protein bioregulators emerged at an early stage during formation of biochemical systems in prokaryotic cells involving protein synthesis on ribosomes, the processes of exo- and endocytosis and limited proteolysis reactions. Primary autocrine bioregulators are compared with growth factors. Models for cellular bioregulation are discussed in which both cell receptors and peptide/protein ligands, primarily immunoglobins, act as prehormones. Their internalization and limited proteolysis can lead to formation of low-molecular peptides (tetines) acting as autocrine or paracrine bioregulators. Basing on the concept of biochemical universality, it is suggested that the effects of many growth factors, hormones, immunoglobulins, mono- and lymphokins are mediated by identical or similar (carrying the same signatures) fragments which are produced in cells due to limited proteolysis reactions and which are directly involved in activation of biochemical systems in these cells.