Mechanisms of protein localization.

A signal sequence mutant defective in export of ribose-binding protein and a corresponding pseudorevertant isolated without imposed selection.

“…We presume that the mutational change in rbsB103 was created by the mutator activity of the parental strain. Almost all signal sequence mutants isolated have been obtained using site-directed mutagenesis (Koshland et al, 1982;Vlasuk et al, 1984) or specialized selection techniques involving gene fusions (reviewed in Silhavy et al, 1983). However, among null mutants missing an exported protein in its proper location, some should be defective not in synthesis but in export of that protein.…”

“…Interpreting effects of alterations in signal sequences A collection of signal sequence mutations in malE (maltosebinding protein) and lamB (lambda receptor) has been obtained by specialized selection techniques involving gene fusions (reviewed by Silhavy et al, 1983). In turn, pseudorevertants exhibiting improved export have been selected from some exportdefective mutants Bankaitis et al, 1984a).…”

Membrane Insertion and Transport of Viral Glycoproteins: A Mutational Analysis

“…We have tested this hypothesis by introducing genetic lesions into the gene encoding the envelope glycoproteins of RSV (Wills et al, 1983(Wills et al, , 1984Hardwick et al, 1986;, as have others for the VSV G protein Bergmann, 1982, 1983;Rose et al, 1984;Adams and Rose, 1985a,b), the influenza virus hemagglutinin protein (Sveda et al, 1982Gething and Sambrook, 1982;Doyle et al, 1985Doyle et al, , 1986Gething et al, 1986), and the glycoproteins of Semliki Forest virus (Garoff et al, 1983;Garoff, 1985;. Genetic analyses of protein transport in prokaryotic systems have provided both support for the role of the signal peptide in protein translocation and valuable insights into the polypeptide interactions that are required for the intracellular targeting of bacterial secreted and membrane proteins (reviewed by Michaelis and Beckwith, 1982;Silhavy et al, 1983;Benson et al, 1985;Oliver, 1985). While similar experiments are more difficult to perform in eukaryotic cells with the enveloped virus systems described here, both the classic and molecular genetic approaches outlined below are providing information on the role of different protein domains in the transport process.…”

“…Three structurally distinct regions have been observed so far: a positively charged aminoterminal region, a central region of 9 or more hydrophobic residues, and a more polar carboxy-terminal region that appears to define the cleavage site (von Heijne, 1983(von Heijne, , 1984(von Heijne, , 1985Perlman and Halvorson, 1983). The importance of these general features has been supported by the genetic studies in prokaryotic systems (reviewed by Silhavy et al, 1983;Benson et al, 1985).…”

“…The mechanisms by which cells send membrane-bound and secreted proteins to their proper subcellular locations remain a central problem in cell biology. It has been postulated to involve the specific interaction of "sorting signals," located within the structure of the newly synthesized proteins, with membrane-bound receptors in the RER and Golgi apparatus of the cell (for review, see Sabatini et al, 1982;Silhavy et al, 1983). This concept is supported by the facts that cell, as well as viral, glycoproteins can be retained at or targeted to specific points in the secretory pathway and that cells can transport and secrete a variety of glycosylated and nonglycosylated proteins at distinctly different rates (Strous and Lodish, 1980;Fitting and Kabat, 1982;Gumbiner and Kelly, 1982;Ledford and Davis, 1983;, Kelly, 1985.…”