Characteristics of the eukaryotic initiation factor 2 associated 67-kDa polypeptide.
A eukaryotic initiation factor 2 (eIF-2) associated 67-kDa polypeptide (p67) protects the eIF-2 alpha-subunit from eIF-2 kinase(s) catalyzed phosphorylation, and this promotes protein synthesis in the presence of active eIF-2 kinase(s), [Datta, B., et al. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 3324-3328]. This report presents the results of studies related to characteristics of p67 action and the mechanism of p67:eIF-2 interaction: (1) p67 antibodies inhibited protein synthesis in hemin-supplemented rabbit reticulocyte lysates, and such inhibition was reversed by preincubation of the antibodies, specifically with p67. (2) p67 inhibited HRI- and dsI-catalyzed phosphorylations of the eIF-2 alpha-subunit and histones, but it did not inhibit casein kinase catalyzed phosphorylation of the eIF-2 beta-subunit. (3) p67 bound specifically to the eIF-2 gamma-subunit. p67 co-immunoprecipitated with the eIF-2 subunits when a p67/eIF-2 mixture was treated with p67 or eIF-2 subunit antibodies and protein A agarose. However, when eIF-2 was preincubated specifically with the eIF-2 gamma-subunit antibodies, subsequent co-immunoprecipitation of p67 with the eIF-2 subunits was completely inhibited. Similarly, preincubation of p67 and p67 antibodies prevented subsequent p67 binding to eIF-2. Preincubation of eIF-2, with either eIF-2 alpha- or beta-subunit antibodies, had no effect on p67 co-immunoprecipitation with the eIF-2 subunits. (4) p67:eIF-2 interaction is necessary for p67 activity to protect the eIF-2 alpha-subunit from eIF-2 kinase(s) catalyzed phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)
Ray
M K
MK
Department of Chemistry, University of Nebraska, Lincoln 68588.
Chakraborty
A
A
Datta
B
B
Chattopadhyay
A
A
Saha
D
D
Bose
A
A
Kinzy
T G
TG
Wu
S
S
Hileman
R E
RE
Merrick
W C
WC
D047388:Casein Kinases; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D015151:Immunoblotting; D007163:Immunosorbent Techniques; D008274:Magnesium / Q000494:pharmacology; D008970:Molecular Weight; D010455:Peptides / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D010766:Phosphorylation; D014176:Protein Biosynthesis; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D019892:eIF-2 Kinase
D015852:Eukaryotic Initiation Factor-2; D006657:Histones; D010455:Peptides; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D047388:Casein Kinases; D019892:eIF-2 Kinase; D008274:Magnesium