The relationship between low density lipoprotein-related protein/alpha 2-macroglobulin (alpha 2M) receptors and the newly described alpha 2M signaling receptor.
alpha 2-Macroglobulin (alpha 2M)-methylamine binding to macrophages appears to involve two receptors. Binding of alpha 2M-methylamine to low density lipoprotein-related protein (LRP) results in cellular uptake and degradation, while binding to a newly described alpha 2M signaling receptor elevates intracellular calcium ([Ca2+]i) and inositol phosphates. We now demonstrate that binding of lactoferrin, Pseudomonas exotoxin A, and lipoprotein lipase to LRP on macrophages results in increased [Ca2+]i and inositol 1,4,5-triphosphate. Receptor-associated protein, which binds to LRP but not the alpha 2M signaling receptor, blocks the lactoferrin signal but has no effect on alpha 2M-methylamine signaling. The latter observation supports our hypothesis that a distinct signaling receptor binds alpha 2M-methylamine. We further demonstrate that the signaling events induced by lactoferrin may involve a pertussis toxin-sensitive G protein, while the alpha 2M signaling receptor appears to be coupled to a pertussis toxin-insensitive G protein.
Duke Scholars
Published In
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- alpha-Macroglobulins
- Virulence Factors, Bordetella
- Time Factors
- Signal Transduction
- Receptors, Immunologic
- Pertussis Toxin
- Mice, Inbred C57BL
- Mice
- Macrophages, Peritoneal
- Low Density Lipoprotein Receptor-Related Protein-1
Citation
Published In
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- alpha-Macroglobulins
- Virulence Factors, Bordetella
- Time Factors
- Signal Transduction
- Receptors, Immunologic
- Pertussis Toxin
- Mice, Inbred C57BL
- Mice
- Macrophages, Peritoneal
- Low Density Lipoprotein Receptor-Related Protein-1