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The mast cell function-associated antigen and its interactions with the type I Fcepsilon receptor
Jinming Song1, Guy M Hagen, Deborah A Roess
1Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, and Department of Immunology, The Weizmann Institute of Science, 76100 Rehovot, Israel.
Biochemistry
|January 16, 2002
Summary
The MAst cell Function-associated Antigen (MAFA) interacts with the type I Fcepsilon receptor (FcepsilonRI) on mast cells. This interaction inhibits normal secretion, revealing a new regulatory mechanism in mast cell degranulation.
Area of Science:
- Immunology
- Cell Biology
- Biophysics
Background:
- Rat RBL-2H3 mast cells express MAst cell Function-associated Antigen (MAFA).
- MAFA clustering inhibits type I Fcepsilon receptor (FcepsilonRI)-mediated secretion.
- The molecular basis of MAFA-FcepsilonRI interaction and inhibition is unknown.
Purpose of the Study:
- To investigate the interaction between MAFA and FcepsilonRI.
- To elucidate the mechanism of MAFA-mediated inhibition of mast cell secretion.
Main Methods:
- Time-resolved phosphorescence anisotropy was used to study the rotational diffusion of MAFA and FcepsilonRI.
- Erythrosin-conjugated IgE and G63 Fab were used to label FcepsilonRI and MAFA, respectively.
- Rotational behavior was analyzed under conditions of FcepsilonRI ligation and MAFA clustering.
Main Results:
- MAFA and FcepsilonRI exhibit similar rotational correlation times, suggesting association.
- Clustering FcepsilonRI with antigen or anti-IgE affects the rotational behavior of MAFA.
- MAFA's lateral diffusion is reduced upon FcepsilonRI clustering.
Conclusions:
- MAFA associates with clustered FcepsilonRI.
- These findings support MAFA's role in regulating FcepsilonRI-mediated mast cell degranulation.
- The study provides insights into the molecular mechanisms of mast cell signaling.