Identification of the substrates of the casein kinase II associated with non-polysomal messenger ribonucleoproteins of A. salina cryptobiotic embryos.
The association of a protein kinase with cytoplasmic non-polysomal messenger ribonucleoproteins is demonstrated by chromatography on oligo(dT)-cellulose and sucrose gradient centrifugation. The cAMP-independent enzyme is inhibited by caffeine and poly(L)-glutamic acid and is classified as a casein kinase II. Among the exogenous proteins initiation factor eIF2 is the best substrate and is 7.8 times more efficiently phosphorylated than casein. Endogenous mRNP protein substrates have a Mr of 125 000, 65 000, 38 000, 26 000 and 23 500. The main phosphate acceptor is the Mr 38 000 poly(A)-binding protein. Dephosphorylation of the poly(A)-binding protein by protein phosphatases decreases its RNA binding property. The effect of phosphorylation-dephosphorylation of mRNP proteins on the initiation of protein synthesis is discussed.
Thoen
C
C
Van Hove
L
L
Slegers
H
H
D000818:Animals; D001156:Artemia / Q000196:embryology / Q000378:metabolism*; D047388:Casein Kinases; D005775:Gastrula / Q000378:metabolism; D010766:Phosphorylation; D011132:Polyribosomes / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism*; D013379:Substrate Specificity
D012333:RNA, Messenger; D012261:Ribonucleoproteins; D011494:Protein Kinases; D047388:Casein Kinases