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UDP-galactose:globoside galactosyltransferase in murine kidney
O Koul1, M Prada-Maluf, R H McCluer
1Department of Biochemistry, E. K. Shriver Center, Waltham, MA 02254.
Journal of Lipid Research
|December 1, 1990
Summary
Male mice exhibit higher kidney globo-series glycolipid levels due to increased UDP-galactose:globoside galactosyltransferase activity. This enzyme
Area of Science:
- Biochemistry
- Glycobiology
- Comparative Physiology
Background:
- Stage-specific embryonic antigens (SSEA-3 and SSEA-1) globo-series glycolipids are present at higher levels in male kidneys compared to female kidneys in DBA/2 and C57BL/6 mouse strains.
- Understanding the enzymatic basis for these sex-specific differences in glycolipid expression is crucial for metabolic pathway analysis.
Purpose of the Study:
- To investigate the activity and properties of UDP-galactose:globoside galactosyltransferase in male and female mouse kidney microsomes.
- To elucidate the enzymatic steps responsible for observed sex-based differences in globo-series glycolipid levels.
Main Methods:
- Enzyme activity assays were performed on kidney microsomes from male and female DBA/2 and C57BL/6 mice.
- High-performance thin-layer chromatography (HPTLC) immunostaining was used to identify the reaction product, galactosylgloboside (a SSEA-3 glycolipid).
- Enzyme properties including optimal pH, cofactor requirements, thermal stability, substrate affinity (Km), and differential activation by detergents (CHAPS, cholate) were analyzed.
Main Results:
- UDP-galactose:globoside galactosyltransferase activity was approximately 2-fold greater in male C57BL/6 mice compared to females, particularly in the presence of CHAPS.
- The enzyme exhibited optimal activity at pH 5.6 and required Mn2+ for maximal function in both sexes and strains.
- While thermal stability was similar, enzyme kinetics (Km) and detergent activation profiles differed between male and female microsomes, suggesting the presence of enzyme modulators.
Conclusions:
- The study identified UDP-galactose:globoside galactosyltransferase as a key enzyme in the sex-specific regulation of globo-series glycolipids in mouse kidneys.
- Differential enzyme activity and modulation by detergents indicate complex regulatory mechanisms contributing to glycolipid level variations between sexes.
- These findings suggest potential sex-based differences in metabolic pathways involving globo-series glycolipids.