Developmental changes in enzymes involved in dolichyl phosphate metabolism in cultured embryonic rat brain cells.
The rates of synthesis of dolichol-linked oligosaccharide intermediates and protein N-glycosylation increased substantially during a developmental period corresponding to glial differentiation in primary cultures of embryonic rat brain. In this study developmental changes in three enzymes involved in dolichyl phosphate (Dol-P) metabolism have been examined by in vitro assays and correlated with the induction pattern for lipid intermediate synthesis and protein N-glycosylation. Dolichyl pyrophosphate (Dol-P-P) phosphatase activity was relatively low during the first 9 days in culture, but it increased significantly between days 9 and 25. Dol-P-P phosphatase did not change appreciably between days 22 and 30 in culture. A kinetic analysis of the developmental change in Dol-P-P phosphatase activity revealed that the Vmax increased 10-fold between days 4 and 22, and there was also a significant change in the apparent Km for Dol-P-P. Dolichol kinase activity increased during the period (9-15 days) when there was a significant induction in oligosaccharide-lipid synthesis and protein N-glycosylation, and then declined in parallel with lipid intermediate synthesis and protein N-glycosylation. Dol-P phosphatase activity was present at relatively low levels for the first 9 days in culture, but it increased steadily between days 9 and 30. A kinetic comparison of the activity in membrane fractions from brain cells cultured for 9 and 25 days indicated that there was a 10-fold increase in enzyme protein with unaltered affinity for Dol-P.(ABSTRACT TRUNCATED AT 250 WORDS)
Bhat
N R
NR
Department of Biochemistry, University of Kentucky College of Medicine, A. B. Chandler Medical Center, Lexington 40536.
Frank
D W
DW
Wolf
M J
MJ
Waechter
C J
CJ
D000818:Animals; D001921:Brain / Q000196:embryology* / Q000201:enzymology; D002454:Cell Differentiation; D002478:Cells, Cultured; D004288:Dolichol Phosphates / Q000378:metabolism*; D006031:Glycosylation; D007700:Kinetics; D009457:Neuroglia / Q000166:cytology; D009844:Oligosaccharides / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D011755:Pyrophosphatases; D051381:Rats; D013997:Time Factors
D004288:Dolichol Phosphates; D009844:Oligosaccharides; D010744:Phosphoric Monoester Hydrolases; D011755:Pyrophosphatases; C023082:dolichyldiphosphatase