Structure of initiation factor eIF-3 from rat liver: hydrodynamic and electron microscopic investigations

On the basis of hydrodynamic, electron microscopic and biochemical investigations a new model of the structure of initiation factor eIF-3 is proposed. From sedimentation and diffusion coefficients of 16.35 S and 2.13 X 10(-7) cm2/s, respectively, as well as from sedimentation equilibrium measurement...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:European journal of biochemistry 1986-06, Vol.157 (3), p.523-530
Hauptverfasser: BEHLKE, J, BOMMER, U.-A, LUTSCH, G, HENSKE, A, BIELKA, H
Format: Artikel
Sprache:eng
Schlagworte:
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:On the basis of hydrodynamic, electron microscopic and biochemical investigations a new model of the structure of initiation factor eIF-3 is proposed. From sedimentation and diffusion coefficients of 16.35 S and 2.13 X 10(-7) cm2/s, respectively, as well as from sedimentation equilibrium measurements, a molecular mass of about 650 kDa was determined for isolated eIF-3. This is in agreement with molecular mass estimations by sodium dodecyl sulphate gel electrophoresis. A partial specific volume of 0.723 cm3/g was determined by means of the amino acid composition and the specific volume increments of the amino acids. From this value and from the molecular mass, a volume of 780 nm3 was calculated for eIF-3. In electron micrographs of isolated eIF-3, images with triangular profiles and side lengths of 14 nm, 16 nm, and 17 nm have been observed. Taking into account the calculated volume and considering the triangular image as one face of the particle, it is suggested that eIF-3 has the shape of a flat triangular prism with a height of about 7 nm and the above-mentioned side-lengths. This model is in agreement with results of electron microscopic investigations of eIF-3 in native small ribosomal subunits [Lutsch, G., Benndorf, R., Westermann, P., Bommer, U.-A. & Bielka, H. (1986) Eur. J. Cell Biol. 40/2, in press]. The high frictional ratio of about 1.7 also supports eIF-3 to be rather of a flat than of a globular shape.
ISSN:0014-2956
1432-1033
DOI:10.1111/j.1432-1033.1986.tb09698.x