TY - JOUR
T1 - Differing effects of the protein phosphatase inhibitors okadaic acid and microcystin on translation in reticulocyte lysates
AU - Redpath, Nicholas T.
AU - Proud, Christopher G.
N1 - Funding Information:
We thank Trish Diggle for help in preparing the anti-eEF-2an tibody and Professor P. Cohen for supplying the okadaic acid. This work was funded by the Medical Research Council and the Science and EngineeringR esearch Council,
PY - 1991/6/7
Y1 - 1991/6/7
N2 - The effects of the cyanobacterial toxin and protein phosphate inhibitor, microcystin, on translation in rabbit reticulocyte lysates have been studied. Microcystin inhibited translation with similar potency to the protein phosphatase inhibitor okadaic acid. Unlike low concentrations of okadaic acid, however, it inhibited both the initiation and elongation stages. This was demonstrated using EGTA to inhibit the phosphorylation and inactivation of elongation factor eEF-2. A method for detecting change in eEF-2 phosphorylation was developed. eEF-2 was found to exist as three different species: eEF-2 was largerly monophosphorylated in reticulocyte lysates under control conditions, the remainder being unphosphorylated. Okadaic acid and microcystin increased the level of the bisphosphorylated species. The implications of multiple phosphorylation of eEF-2 for the control of translation is discussed. Microcystin was also found to increase the phosphorylation of eIF-2α (and therefore to inhibit initiation) at lower concentrations than okadaic acid, suggesting that the major eIF-2α phosphatase in the reticulocyte lysate is phosphatase-1.
AB - The effects of the cyanobacterial toxin and protein phosphate inhibitor, microcystin, on translation in rabbit reticulocyte lysates have been studied. Microcystin inhibited translation with similar potency to the protein phosphatase inhibitor okadaic acid. Unlike low concentrations of okadaic acid, however, it inhibited both the initiation and elongation stages. This was demonstrated using EGTA to inhibit the phosphorylation and inactivation of elongation factor eEF-2. A method for detecting change in eEF-2 phosphorylation was developed. eEF-2 was found to exist as three different species: eEF-2 was largerly monophosphorylated in reticulocyte lysates under control conditions, the remainder being unphosphorylated. Okadaic acid and microcystin increased the level of the bisphosphorylated species. The implications of multiple phosphorylation of eEF-2 for the control of translation is discussed. Microcystin was also found to increase the phosphorylation of eIF-2α (and therefore to inhibit initiation) at lower concentrations than okadaic acid, suggesting that the major eIF-2α phosphatase in the reticulocyte lysate is phosphatase-1.
KW - Elongation factor-2
KW - Initiation factor-2
KW - Microcystin
KW - Okadaic acid
KW - Protein phosphorylation
KW - Protein synthesis
UR - http://www.scopus.com/inward/record.url?scp=0025805608&partnerID=8YFLogxK
U2 - 10.1016/0167-4889(91)90135-K
DO - 10.1016/0167-4889(91)90135-K
M3 - Article
C2 - 1646647
AN - SCOPUS:0025805608
VL - 1093
SP - 36
EP - 41
JO - Biochimica et Biophysica Acta - Molecular Cell Research
JF - Biochimica et Biophysica Acta - Molecular Cell Research
SN - 0167-4889
IS - 1
ER -