Perspectives in S-100 protein biology. Review article.
The S-100 protein family constitutes a subgroup of Ca(2+)-binding proteins of the EF-hand type comprising three dimeric isoforms, S-100a0, S-100a and S-100b, plus a number of structurally related proteins displaying 28-55% homology with S-100 subunits. S-100 protein was discovered in 1965; yet, its biological functions have not been fully elucidated. The present report will review the putative biological roles of S-100 protein. Both intracellular and extracellular roles have been proposed for S-100 protein. Within cells, S-100 protein has been reported to regulate protein phosphorylation, ATPase, adenylate cyclase, and aldolase activities and Ca(2+)-induced Ca2+ release. Also, cytoskeletal systems, namely microtubules and microfilaments have been reported to be regulated by the protein in the presence of Ca2+. Some molecular targets of S-100 protein within cells, have been identified. This is the case with microtubule proteins, caldesmon, and a brain aldolase. S-100 protein has been reported to be secreted; extracellular S-100 protein can stimulate neuronal differentiation, glial proliferation, and prolactin secretion. However, the mechanisms by which S-100 is secreted and stimulates the above processes are largely unknown. Future research should characterize these latter aspects of S-100 biology and find out the linkage between its intracellular effects and its extracellular activities.
Donato
R
R
Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Italy.
D002118:Calcium / Q000378:metabolism*; D002453:Cell Cycle; D002462:Cell Membrane / Q000378:metabolism; D002891:Chromosomes, Human, Pair 21; D003599:Cytoskeleton / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D009418:S100 Proteins / Q000737:chemistry / Q000502:physiology*
D011506:Proteins; D009418:S100 Proteins; D002118:Calcium