Biomaterial Database

Glycosylation of eukaryotic peptide chain initiation factor 2 (eIF-2)-associated 67-kDa polypeptide (p67) and its possible role in the inhibition of eIF-2 kinase-catalyzed phosphorylation of the eIF-2 alpha-subunit. 1989

B Datta, and M K Ray, and D Chakrabarti, and D E Wylie, and N K Gupta

Department of Chemistry, School of Biological Sciences, University of Nebraska, Lincoln 68588-0304.

We have reported previously that a 67-kDa polypeptide (p67) present in reticulocyte lysates protects the alpha-subunit of reticulocyte eukaryotic peptide chain initiation factor 2 (eIF-2) from phosphorylation by an eIF-2 kinase, heme-regulated protein synthesis inhibitor (Datta, B., Chakrabarti, D., Roy, A.L., and Gupta, N. K. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 3324-3328). We now present evidence that this p67 contains multiple O-linked N-acetylglucosamine (GlcNAc) residues, and these glycosyl residues may be required for p67 activity to protect the eIF-2 alpha-subunit from eIF-2 kinase phosphorylation. Our results are as follows. 1) p67 binds specifically to wheat germ agglutinin, and such binding is completely inhibited in the presence of 0.2 M GlcNAc. 2) The binding of p67 to wheat germ agglutinin leads to complete loss of p67 activity to protect the eIF-2 alpha-subunit from eIF-2 kinase phosphorylation. 3) p67 accepts 10-12 [3H]galactose molecules from UDP-[3H]galactose in the presence of galactosyltransferase. This radioactivity is resistant to endo-beta-N-acetylglucosamine F (+ peptide:N-glycosidase F) treatment but is completely lost when the 3H-labeled p67 is treated with sodium borohydride in mild alkali (beta-elimination reaction). These results suggest that p67 contains terminal GlcNAc moieties O-linked to the protein. 4) Upon hexosaminidase treatment, p67 reaction product migrated as a lower molecular mass (Mr approximately 65 kDa) protein in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 5) A monoclonal antibody (D1) against p67 has been isolated. D1 apparently recognizes a specific GlcNAc-containing peptide epitope in p67 and does not react with hexosaminidase-treated p67. These results suggest that p67 activity in the cell may also be regulated post-transcriptionally by glycosylation of p67 protein.

UI	MeSH Term	Description	Entries
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D010766	Phosphorylation	The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.	Phosphorylations
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011494	Protein Kinases	A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.	Protein Kinase,Kinase, Protein,Kinases, Protein
D012156	Reticulocytes	Immature ERYTHROCYTES. In humans, these are ERYTHROID CELLS that have just undergone extrusion of their CELL NUCLEUS. They still contain some organelles that gradually decrease in number as the cells mature. RIBOSOMES are last to disappear. Certain staining techniques cause components of the ribosomes to precipitate into characteristic "reticulum" (not the same as the ENDOPLASMIC RETICULUM), hence the name reticulocytes.	Reticulocyte
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D003126	Colostrum	The thin, yellow, serous fluid secreted by the mammary glands during pregnancy and immediately postpartum before lactation begins. It consists of immunologically active substances, white blood cells, water, protein, fat, and carbohydrates.	Colostrums
D005260	Female		Females
D005700	Galactosyltransferases	Enzymes that catalyze the transfer of galactose from a nucleoside diphosphate galactose to an acceptor molecule which is frequently another carbohydrate. EC 2.4.1.-.	Galactosyltransferase
D006026	Glycoside Hydrolases	Any member of the class of enzymes that catalyze the cleavage of the glycosidic linkage of glycosides and the addition of water to the resulting molecules.	Endoglycosidase,Exoglycosidase,Glycohydrolase,Glycosidase,Glycosidases,Glycoside Hydrolase,Endoglycosidases,Exoglycosidases,Glycohydrolases,Hydrolase, Glycoside,Hydrolases, Glycoside