Fibroblast membrane sterol kinetic domains: modulation by sterol carrier protein-2 and liver fatty acid binding protein
The mechanism(s) of intracellular sterol trafficking among subcellular organelle membranes is not well understood. Relative contributions of vesicular, sterol carrier protein, and membrane sterol domain pathways are not resolved. A sterol kinetic assay was used to resolve multiple sterol domains in...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
1996-09-01
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| Series: | Journal of Lipid Research |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022227520375519 |
| _version_ | 1818725573095063552 |
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| author | A Frolov J K Woodford E J Murphy J T Billheimer F Schroeder |
| author_facet | A Frolov J K Woodford E J Murphy J T Billheimer F Schroeder |
| author_sort | A Frolov |
| collection | DOAJ |
| description | The mechanism(s) of intracellular sterol trafficking among subcellular organelle membranes is not well understood. Relative contributions of vesicular, sterol carrier protein, and membrane sterol domain pathways are not resolved. A sterol kinetic assay was used to resolve multiple sterol domains in microsome (MICRO), mitochondria (MITO), and plasma (PM) membrane: exchangeable, 20-40% of total; non-exchangeable, 60-80% of total. Spontaneous sterol transfer between dissimilar donor and acceptor membranes was vectorial and depended both on acceptor and donor membrane properties. For example, sterol transfer from PM to MICRO or to MITO, or from MICRO to MITO was 3- to 5-fold slower as compared to sterol movement in the opposite direction. Sterol carrier protein-2 (SCP-2) stimulated sterol transfer in most donor/acceptor membrane combinations by decreasing exchange half-time but not domain size. SCP-2 enhanced sterol transfer selectively: PM-MICRO (12-fold); MITO-MITO, MICRO-MICRO, MICRO-PM (3-fold); PM-PM (1.4-fold); PM-MITO, MICRO-MITO (no effect). Thus, SCP-2-mediated sterol movement was vectorial and not necessarily down a membrane sterol concentration gradient. In contrast, liver fatty acid binding protein (L-FABP) revealed a modest (2-fold) stimulatory effect on sterol transfer only between PM-MITO and MICRO-MICRO. In conclusion, in vitro studies of sterol transfer among isolated subcellular membranes provided kinetic evidence for sterol domains in microsomes and mitochondria as well as plasma membranes. Furthermore, both spontaneous and protein-mediated sterol transfer appeared vectorial and selective in nature. |
| first_indexed | 2024-12-17T21:44:27Z |
| format | Article |
| id | doaj.art-ea8283acdf764bbaa2603426162a6154 |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-12-17T21:44:27Z |
| publishDate | 1996-09-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-ea8283acdf764bbaa2603426162a61542022-12-21T21:31:31ZengElsevierJournal of Lipid Research0022-22751996-09-0137918621874Fibroblast membrane sterol kinetic domains: modulation by sterol carrier protein-2 and liver fatty acid binding proteinA Frolov0J K Woodford1E J Murphy2J T Billheimer3F Schroeder4Department of Physiology and Pharmacology, Texas A & M University, TVMC, College Station 77843-4466, USA.Department of Physiology and Pharmacology, Texas A & M University, TVMC, College Station 77843-4466, USA.Department of Physiology and Pharmacology, Texas A & M University, TVMC, College Station 77843-4466, USA.Department of Physiology and Pharmacology, Texas A & M University, TVMC, College Station 77843-4466, USA.Department of Physiology and Pharmacology, Texas A & M University, TVMC, College Station 77843-4466, USA.The mechanism(s) of intracellular sterol trafficking among subcellular organelle membranes is not well understood. Relative contributions of vesicular, sterol carrier protein, and membrane sterol domain pathways are not resolved. A sterol kinetic assay was used to resolve multiple sterol domains in microsome (MICRO), mitochondria (MITO), and plasma (PM) membrane: exchangeable, 20-40% of total; non-exchangeable, 60-80% of total. Spontaneous sterol transfer between dissimilar donor and acceptor membranes was vectorial and depended both on acceptor and donor membrane properties. For example, sterol transfer from PM to MICRO or to MITO, or from MICRO to MITO was 3- to 5-fold slower as compared to sterol movement in the opposite direction. Sterol carrier protein-2 (SCP-2) stimulated sterol transfer in most donor/acceptor membrane combinations by decreasing exchange half-time but not domain size. SCP-2 enhanced sterol transfer selectively: PM-MICRO (12-fold); MITO-MITO, MICRO-MICRO, MICRO-PM (3-fold); PM-PM (1.4-fold); PM-MITO, MICRO-MITO (no effect). Thus, SCP-2-mediated sterol movement was vectorial and not necessarily down a membrane sterol concentration gradient. In contrast, liver fatty acid binding protein (L-FABP) revealed a modest (2-fold) stimulatory effect on sterol transfer only between PM-MITO and MICRO-MICRO. In conclusion, in vitro studies of sterol transfer among isolated subcellular membranes provided kinetic evidence for sterol domains in microsomes and mitochondria as well as plasma membranes. Furthermore, both spontaneous and protein-mediated sterol transfer appeared vectorial and selective in nature.http://www.sciencedirect.com/science/article/pii/S0022227520375519 |
| spellingShingle | A Frolov J K Woodford E J Murphy J T Billheimer F Schroeder Fibroblast membrane sterol kinetic domains: modulation by sterol carrier protein-2 and liver fatty acid binding protein Journal of Lipid Research |
| title | Fibroblast membrane sterol kinetic domains: modulation by sterol carrier protein-2 and liver fatty acid binding protein |
| title_full | Fibroblast membrane sterol kinetic domains: modulation by sterol carrier protein-2 and liver fatty acid binding protein |
| title_fullStr | Fibroblast membrane sterol kinetic domains: modulation by sterol carrier protein-2 and liver fatty acid binding protein |
| title_full_unstemmed | Fibroblast membrane sterol kinetic domains: modulation by sterol carrier protein-2 and liver fatty acid binding protein |
| title_short | Fibroblast membrane sterol kinetic domains: modulation by sterol carrier protein-2 and liver fatty acid binding protein |
| title_sort | fibroblast membrane sterol kinetic domains modulation by sterol carrier protein 2 and liver fatty acid binding protein |
| url | http://www.sciencedirect.com/science/article/pii/S0022227520375519 |
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