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Location of NRAMP1 molecule on the plasma membrane and its association with microtubules
Abstract:
Natural resistance to infection with intracellular parasites, such as Leishmania, Salmonella, and Mycobacterium, is controlled in mice by the expression of a single dominant gene locus designated Lsh/Ity/Bcg. Natural resistance-associated macrophage protein gene 1 (NRAMP1) was isolated as a candidate gene. NRAMP1 encodes an M(r) 60000 polypeptide with 10-12 potential transmembrane domains and an evolutionary conserved consensus transport motif. The present study shows that the human NRAMP1 molecule is expressed in all cell lineages of macrophage/monocyte and B- and T-lymphocytes. Immunohistochemical analysis using antihuman NRAMP1 antibody provides the direct evidence that the NRAMP1 molecule is located and distributed on the plasma membrane. An NRAMP1-glutathione S-transferase (GST) fusion protein was used to affinity-purify a protein, bound to the NH2-terminal cytoplasmic domain of NRAMP1. It was found that the NRAMP1 molecule was associated with alpha- and beta-tubulin of microtubules. These results suggest that NRAMP1 may function as a molecule, possessing the abilities of membrane-anchoring and microtubule-binding, for the microtubule-mediated transport of vesicles and be a new class of microtubule-associated proteins.
Insights
Natural resistance to intracellular parasites is linked to the Natural Resistance-Associated Macrophage Protein 1 (NRAMP1) gene. This study reveals NRAMP1
Area of Science:
- Immunology
- Cell Biology
- Genetics
Background:
- Innate immunity to intracellular pathogens like Leishmania, Salmonella, and Mycobacterium is genetically controlled in mice by the Lsh/Ity/Bcg gene locus.
- Natural Resistance-Associated Macrophage Protein 1 (NRAMP1) was identified as a candidate gene for this resistance.
- NRAMP1 encodes a protein with transmembrane domains and a conserved transport motif.
Purpose of the Study:
- To investigate the expression and cellular localization of the human NRAMP1 molecule.
- To identify proteins that interact with NRAMP1.
- To elucidate the potential function of NRAMP1 in cellular processes.
Main Methods:
- Immunohistochemical analysis using anti-human NRAMP1 antibody.
- Expression analysis in various immune cell lineages (macrophage/monocyte, B- and T-lymphocytes).
- Affinity purification using an NRAMP1-glutathione S-transferase (GST) fusion protein to identify binding partners.
Main Results:
- Human NRAMP1 is expressed in macrophage/monocyte and B- and T-lymphocyte lineages.
- Immunohistochemistry confirmed NRAMP1 localization on the plasma membrane.
- NRAMP1 was found to associate with alpha- and beta-tubulin, components of microtubules.
Conclusions:
- NRAMP1 is expressed on the plasma membrane of key immune cells.
- NRAMP1 interacts with microtubules, suggesting a role in microtubule-mediated transport.
- NRAMP1 may function as a novel microtubule-associated protein involved in vesicle transport.