Site of stimulation by mannosyl-P-dolichol of GlcNAc-lipid formation by microsomes of embryonic chick retina

被引:7
作者
Kean, EL [1 ]
机构
[1] CASE WESTERN RESERVE UNIV,DEPT BIOCHEM,CLEVELAND,OH 44106
关键词
mannosyl-P-dolichol; GlcNAc-P-P-dolichol; GlcNAc-GlcNAc-P-P-dolichol; site of stimulation; retina;
D O I
10.1007/BF00731456
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Mannosyl-P-dolichol (man-P-dol) has been shown to stimulate the early reactions of the dolichol pathway, specifically, the biosynthesis of GlcNAc-P-P-dol and GlcNAc-GlcNAc-P-P-dol, and thus may play a regulatory role in glycoprotein biosynthesis. The site of action of man-P-dol has previously been suggested to be the GlcNAc-transferase concerned with the formation of the monoglucosaminyl derivative. Since the concentration of the chitobiosyl compound also increases as a result of the presence of man-P-dol, the immediate site of the activation was reexamined. The effect of man-P-dol on the formation of GlcNAc-GlcNAc-P-P-dol using GlcNAc-P-P-dol synthesized in situ or added exogenously as the substrate was investigated. In addition, the distribution of radioactivity in the glucosaminyl constituents of the products under the stimulatory conditions was determined. The results of these studies supported the conclusion that the stimulation of GlcNAc-lipid synthesis by man-P-dol is due to the enhanced synthesis of GlcNAc-P-P-dol. It is not a result of the activation of the GlcNAc-transferase catalyzing the attachment of the second GlcNAc residue for the biosynthesis of the chitobiosyl derivative.
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页码:675 / 680
页数:6
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