Abstract
To exhibit chemotaxis, the orientation of locomotion along a chemical gradient cells sense differences in concentrations of a chemotactic factor by detecting some difference in the occupancy of their chemotactic receptors. Thus chemotaxis is sensitive to the number of receptors present and might be used to evaluate the consequences of receptor down-regulation. The ability of rabbit peritoneal polymorphonuclear leukocytes (PMNs) to orient to a standard gradient at various concentrations of N-formylnorleucylleucylphenylalanine (FNLLP) was examined. The observed orientation was compared to that expected if the directional signal were proportional to a difference in the absolute number or the fractional number of receptors occupied. The receptor occupancy in varying gradients was calculated from the binding constant of FNLLP, 2 X 10(-8) M (Zigmond and Sullivan, 1979, J. Cell Biol. 82:517-527), and the receptor number (a) present initially or (b) present after down-regulation (Sullivan and Zigmond, 1980, J. Cell Biol. 85:703-711). The observed concentration dependence of cell orientation is similar to the change in the number of receptors occupied, the receptor number being corrected for down-regulated cells. The net effect of receptor loss appears to be a decreased sensitivity to gradients at high concentrations of peptide.
Full Text
The Full Text of this article is available as a PDF (396.3 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Berg H. C., Purcell E. M. Physics of chemoreception. Biophys J. 1977 Nov;20(2):193–219. doi: 10.1016/S0006-3495(77)85544-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Catt K. J., Harwood J. P., Aguilera G., Dufau M. L. Hormonal regulation of peptide receptors and target cell responses. Nature. 1979 Jul 12;280(5718):109–116. doi: 10.1038/280109a0. [DOI] [PubMed] [Google Scholar]
- Dahlquist F. W., Elwell R. A., Lovely P. S. Studies of bacterial chemotaxis in defined concentration gradients. A model for chemotaxis toward L-serine. J Supramol Struct. 1976;4(3):329–342. doi: 10.1002/jss.400040304. [DOI] [PubMed] [Google Scholar]
- Sullivan S. J., Zigmond S. H. Chemotactic peptide receptor modulation in polymorphonuclear leukocytes. J Cell Biol. 1980 Jun;85(3):703–711. doi: 10.1083/jcb.85.3.703. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zigmond S. H. Ability of polymorphonuclear leukocytes to orient in gradients of chemotactic factors. J Cell Biol. 1977 Nov;75(2 Pt 1):606–616. doi: 10.1083/jcb.75.2.606. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zigmond S. H., Sullivan S. J. Sensory adaptation of leukocytes to chemotactic peptides. J Cell Biol. 1979 Aug;82(2):517–527. doi: 10.1083/jcb.82.2.517. [DOI] [PMC free article] [PubMed] [Google Scholar]