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Subcellular localization of microsomal triglyceride transfer protein.
Larry L Swift1, Mei-Ying Zhu, Bharati Kakkad
1Department of Pathology, Vanderbilt University School of Medicine, C-3321 Medical Center North, Nashville, TN 37232-2561, USA. larry.swift@vanderbilt.edu
Journal of Lipid Research
|July 3, 2003
Summary
Microsomal triglyceride transfer protein (MTP) is crucial for lipoprotein assembly. This study confirms MTP
Area of Science:
- Cell Biology
- Biochemistry
- Lipid Metabolism
Background:
- Microsomal triglyceride transfer protein (MTP) is essential for assembling apolipoprotein B-containing lipoproteins.
- MTP functions in the endoplasmic reticulum by transferring lipids to forming lipoproteins.
- Emerging evidence suggested a potential role for MTP within the Golgi apparatus.
Purpose of the Study:
- To investigate the hypothesis that MTP functions within the Golgi apparatus.
- To determine the subcellular localization of MTP in mouse liver and cultured cells.
Main Methods:
- Development of a polyclonal antibody against MTP.
- Western blot analysis of hepatic Golgi-rich fractions.
- In vitro lipid transfer assays.
- Immunohistochemistry on mouse liver.
- Confocal microscopy and morphometric analysis in McArdle-RH7777 cells using Golgi markers TGN38 and GS28.
Main Results:
- MTP and triglyceride transfer activity were detected in mouse hepatic Golgi fractions.
- Immunohistochemistry showed MTP present in all hepatocytes.
- Confocal microscopy revealed MTP colocalization with trans-Golgi network (TGN38) and cis-Golgi (GS28) markers in McA cells.
Conclusions:
- This study provides definitive evidence for MTP localization within the Golgi apparatus.
- The findings underscore the Golgi apparatus's significant role in lipoprotein assembly.
- MTP's presence in the Golgi suggests a broader function beyond the endoplasmic reticulum.