Plant 14-3-3 protein families: evidence for isoform-specific functions?
14-3-3 proteins regulate a wide range of target proteins via direct protein-protein interactions. The target-binding domain in 14-3-3 proteins is highly conserved, suggesting similar biochemical properties for all 14-3-3s. However, higher eukaryotes possess multiple 14-3-3 genes, and these genes exhibit diverse patterns of gene expression within any one organism. This tends to suggest specific functions for particular genes. Some biochemical data suggest 14-3-3 isoform-specific protein-protein interactions, whereas other studies conclude that apparent isoform-specificity is the result of differences in expression patterns rather than in the biochemical properties of 14-3-3 isoforms. Here we discuss evidence that demonstrates that the expression levels of 14-3-3 proteins in cells are important for regulating the activity of their target proteins, and further that the elimination of individual 14-3-3 isoforms can result in detectable phenotypes. We also examine evidence that 14-3-3 isoform specificity can in some cases reflect differing biochemical properties as well as differential transcriptional regulation.
Department of Biological Sciences, IENS, Lancaster University, Lancaster LA1 4YQ, UK. m.r.roberts@lancaster.ac.uk
M R
MR
Roberts
G L
GL
de Bruxelles
D048948:14-3-3 Proteins; D018506:Gene Expression Regulation, Plant; D007527:Isoenzymes / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology*; D010944:Plants / Q000201:enzymology* / Q000235:genetics; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism*
D048948:14-3-3 Proteins; D007527:Isoenzymes; D014446:Tyrosine 3-Monooxygenase