This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.107.121822v1 94/7/2884    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by García-Marcos, A. Articles by Ballesta, J. P. G. Search for Related Content PubMed PubMed Citation Articles by García-Marcos, A. Articles by Ballesta, J. P. G.

Yeast Ribosomal Stalk Heterogeneity In Vivo Shown by Two-Photon FCS and Molecular Brightness Analysis

Alberto García-Marcos ^*, Susana A. Sánchez , Pilar Parada ^*, John Eid , David M. Jameson , Miguel Remacha ^*, Enrico Gratton  and Juan P. G. Ballesta ^*

^* Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, 28049 Madrid, Spain; Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California at Irvine, Irvine, California 92697-2715; Pacific Biosciences, Menlo Park, California 94025; and Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii 96813

Correspondence: Address reprint requests to Juan P. G. Ballesta, Centro de Biología Molecular Severo Ochoa, Canto Blanco, 28049 Madrid, Spain. Tel.: 34-91-1964505; Fax: 34 91-1964420; E-mail: jpgballesta{at}cbm.uam.es.

The stalk of Saccharomyces cerevisiae ribosomes contains, on average, five distinct proteins, namely P0 and four acidic proteins, P1, P1β, P2, and P2β. Each ribosome contains only one copy of P0, but the distribution of the acidic proteins among the ribosome population in vivo has not been determined. Using two-photon fluorescence correlation spectroscopy and scanning FCS, on cells expressing EGFP-tagged P0, P1, and P2 proteins, we show, with brightness analysis, that individual yeast ribosomes in vivo are compositionally heterogeneous in regard to P1, P1β, P2, and P2β. These results are relevant to the hypothesis, based on in vitro studies, that the overall cellular pattern of expressed proteins can be determined by the distribution of the stalk proteins among the ribosome population.