title: Surveying the floodgates: estimating protein flux into the endoplasmic reticulum lumen in Saccharomyces cerevisiae.
abstract: Endoplasmic reticulum resident proteins, along with all proteins traveling through the secretory pathway must enter endoplasmic reticulum lumen through membrane-embedded translocons. In Saccharomyces cerevisiae the heterotrimeric endoplasmic reticulum translocon is composed of the Sec61p, Sss1p, and Sbh1p core subunits. While the involvement of various molecules associated with the Sec61 complex has been thoroughly characterized, little attention has been given to the overall flux through these channels. In this work we carried out a meta-analysis to estimate the average and absolute flux of proteins into the endoplasmic reticulum lumen. We estimate an average of 460 proteins enter the endoplasmic reticulum every second, with an absolute minimum and maximum flux of 78 and 3700 molecules per second, respectively. With current technologies limiting the ability to obtain accurate measurements of these events, our estimates shed light on the flow of protein entering the endoplasmic reticulum lumen.
authors.affiliation: Department of Molecular & Integrative Physiology, University of Michigan Medical School Ann Arbor, MI, USA ; Department of Molecular, Cellular, and Developmental Biology, University of Michigan Ann Arbor, MI, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Vincent
authors.affiliation: Department of Molecular & Integrative Physiology, University of Michigan Medical School Ann Arbor, MI, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Whidden
authors.affiliation: Department of Molecular & Integrative Physiology, University of Michigan Medical School Ann Arbor, MI, USA ; Department of Computational Medicine & Bioinformatics, University of Michigan Medical School Ann Arbor, MI, USA ; Brehm Center for Diabetes Research, University of Michigan Medical School Ann Arbor, MI, USA.
authors.forename: Santiago
authors.initials: S
authors.lastname: Schnell
keywords: Sec61; endoplasmic reticulum; protein flux; protein import; translocon; unfolded protein response