title: Efficiency of complex production in changing environment.
abstract: BACKGROUND
  Cell function necessitates the assemblage of proteins into complexes, a process which requires further regulation on top of the fairly understood mechanisms used to control the transcription and translation of a single protein. However, not much is known about how protein levels are controlled to realize that regulation.
  
  
  RESULTS
  We integrated data on the composition of yeast protein complexes and the dynamics of their protein building-blocks concentrations to show how the cell regulates protein levels to optimize complex formation. We find that proteins which are subunits of the same complex tend to have similar levels which change similarly following a change in growth conditions, and that abundant proteins undergo larger decrease in their copy number when grown in minimal media. We also study the fluctuations in protein levels and find them to be significantly smaller in large complexes, and in the least abundant subunit of each complex. We use a mathematical model of complex synthesis to explain how all these observations increase the efficiency of complex synthesis, in terms of better utilization of the available molecules and better resilience to stochastic variations.
  
  
  CONCLUSIONS
  In conclusion, these results indicate an intricate regulation at all levels of protein production for the purpose of optimizing complex formation.
authors.affiliation: Minerva Center & Department of Physics, Bar-Ilan University, Ramat Gan, Israel. scarmi@shoshi.ph.biu.ac.il
authors.forename: Shai
authors.initials: S
authors.lastname: Carmi
authors.forename: Erez Y
authors.initials: EY
authors.lastname: Levanon
authors.forename: Eli
authors.initials: E
authors.lastname: Eisenberg
mesh_terms: D030562:Databases, Protein; D007700:Kinetics; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D014176:Protein Biosynthesis; D021122:Protein Subunits; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D013269:Stochastic Processes; D049490:Systems Biology
chemical_list: D046912:Multiprotein Complexes; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins