Signal recognition-like particles are present in maize.
We show that maize storage protein translocation across microsomal membranes is mediated by signal recognition particles (SRPs) similar to those described in animal systems (Dobberstein, B. (1978) Hoppe-Seyler's Z. Physiol. Chem. 252, 955-962; Walter, P., and Blobel, G. (1980) Proc. Natl. Acad. Sci. U. S. A. 77, 7112-7116). We have prepared a high salt extract from endosperm cell homogenates, from which a ribosome-free fraction was obtained. This fraction is enriched in an SRP-like factor which apparently corresponds to a ribonucleoprotein particle that sediments at about 12 S. The RNA moiety of this 12 S particle is complex, showing a three-band electrophoretic pattern and sedimenting at about 8 S. The fraction restores translocation competence of salt-washed maize microsomes as tested by using a pre-zein message. In contrast to canine SRPs, the maize SRP-like component does not cause a translation arrest of maize storage proteins (zein) in a wheat germ cell-free system.
Campos
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Departamento de Biologia Molecular i Agrobiologia, Centre d'Investigació i Desenvolupament Consejo Superior de Investigacions Cientificas, Jordi Girona Salgado, Barcelona, Spain.
Palau
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Torrent
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Ludevid
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D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D008836:Micrococcal Nuclease / Q000494:pharmacology; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D010179:Pancreas / Q000648:ultrastructure; D010944:Plants / Q000032:analysis*; D014176:Protein Biosynthesis; D012313:RNA / Q000032:analysis; D012261:Ribonucleoproteins / Q000032:analysis* / Q000494:pharmacology; D018271:Signal Recognition Particle; D014158:Transcription, Genetic; D003313:Zea mays; D015028:Zein / Q000235:genetics / Q000378:metabolism
D012261:Ribonucleoproteins; D018271:Signal Recognition Particle; D012313:RNA; D015028:Zein; D008836:Micrococcal Nuclease