Cytoplasmic heat shock granules are formed from precursor particles and are associated with a specific set of mRNAs.
In heat-shocked tomato cell cultures, cytoplasmic heat shock granules (HSGs) are tightly associated with a specific subset of mRNAs coding mainly for the untranslated control proteins. This messenger ribonucleoprotein complex was banded in a CsCl gradient after fixation with formaldehyde (approximately 1.30 g/cm3). It contains all the heat shock proteins and most of the RNA applied to the gradient. During heat shock, a reversible aggregation of HSGs from 15S precursor particles can be shown. These pre-HSGs are not identical to the 19S plant prosomes. Ultrastructural analysis supports the ribonucleoprotein nature of HSGs and their composition of approximately 10-nm precursor particles. A model summarizes our results. It gives a reasonable explanation for the striking conservation of untranslated mRNAs during heat shock and may apply also to animal cells.
Nover
L
L
Institute of Plant Biochemistry, Academy of Sciences of the GDR, Halle.
Scharf
K D
KD
Neumann
D
D
D003594:Cytoplasmic Granules / Q000378:metabolism / Q000648:ultrastructure; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D008854:Microscopy, Electron; D008954:Models, Biological; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics; D010944:Plants / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*
D006360:Heat-Shock Proteins; D010940:Plant Proteins; D011498:Protein Precursors; D012333:RNA, Messenger