| Autor: |
Shaikhin SM; Ajtkhozhin Institute of Molecular Biology and Biochemistry, Kazakh Academy of Sciences, Alma-Ata, Michurina, Kazakhstan., Smailov SK, Lee AV, Kozhanov EV, Iskakov BK |
| Jazyk: |
angličtina |
| Zdroj: |
Biochimie [Biochimie] 1992 May; Vol. 74 (5), pp. 447-54. |
| DOI: |
10.1016/0300-9084(92)90085-s |
| Abstrakt: |
The wheat germ translation initiation factor 2 (WGeIF-2) was isolated in a homogeneous state by an efficient procedure and characterized. Its molecular mass, as determined by a gel-filtration method is approximately 150,000 Da. According to SDS-PAGE WGeIF-2 consists of four subunits with M(r) 37,000 (alpha), 40,000 (beta), 42,000 (gamma) and 52,000 (delta). The beta- and gamma-subunits (but not the alpha-subunit) of WGeIF-2 can be readily phosphorylated by the double-stranded RNA activated kinase isolated from rabbit reticulocytes. Dissociation constants for WGeIF-2 complexes with GDP and GTP were measured. In our evaluation the WGeIF-2 affinity for GDP (KdGDP = 1.5 x 10(-7) M) was only 10 times higher than for GTP (KdGTP = 1.5 x 10(-6) M), while for rabbit reticulocyte eIF-2 (RReIF-2) the difference has been estimated as as much as two orders of magnitude in accordance with the literature. Close values of dissociation constants for WGeIF-2 complexes with guanine nucleotides suggest that at a sufficiently high [GTP]/[GDP] ratio the nucleotide exchange in wheat cells may take place without the participation of specific factor (eIF-2B) which catalyzes the nucleotide exchange on eIF-2 from mammalian cells. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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