Related Experiment Videos
Lateral mobility of Fc gamma RIIa is reduced by protein kinase C activation
1Department of Cell Biology and Anatomy, University of North Carolina at Chapel Hill 27599-7090, USA.
Abstract:
The lateral mobility of membrane proteins can reflect the extent of various protein-protein interactions. Using the fluorescence recovery after photobleaching technique, we have studied the lateral mobility of human Fc gamma RIIa and some Fc gamma RIIa mutants expressed in either P388D1 cells, a mouse macrophage-like cell line, or in Chinese hamster ovary (CHO) cells [1]. After treatment with phorbol myristate acetate (PMA), only the Fc gamma RIIa molecules capable of mediating rapid endocytosis of immune complexes exhibited a reduced lateral diffusion coefficient with respect to untreated controls. Wild type Fc gamma RIIa expressed in CHO cells, and nonfunctional Fc gamma RIIa mutants expressed in P388D1 cells did not show any differences upon PMA treatment. This finding suggests that protein kinase C activation evokes additional protein-protein interactions with the cytoplasmic domain of functional Fc gamma RIIa, which reduced receptor lateral mobility. The identity of these putative interacting proteins and the nature of the interactions remain to be elucidated.
Insights
Phorbol myristate acetate (PMA) treatment reduced the lateral mobility of functional Fc gamma RIIa, indicating new protein interactions. Non-functional mutants and wild-type receptors showed no change, suggesting specific interactions with the cytoplasmic domain.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Membrane protein lateral mobility is crucial for cellular functions.
- Fc gamma RIIa plays a role in immune complex uptake and signaling.
- Protein-protein interactions influence receptor dynamics.
Purpose of the Study:
- To investigate the effect of protein kinase C activation on Fc gamma RIIa lateral mobility.
- To explore potential protein-protein interactions mediated by functional Fc gamma RIIa.
Main Methods:
- Utilized fluorescence recovery after photobleaching (FRAP) to measure lateral diffusion.
- Expressed human Fc gamma RIIa and mutants in P388D1 and CHO cells.
- Treated cells with phorbol myristate acetate (PMA) to activate protein kinase C.
Main Results:
- PMA treatment significantly reduced the lateral diffusion coefficient of functional Fc gamma RIIa.
- Non-functional Fc gamma RIIa mutants and wild-type receptors in CHO cells showed no change in mobility upon PMA treatment.
- This suggests PMA induces specific protein-protein interactions with the functional Fc gamma RIIa cytoplasmic domain.
Conclusions:
- Protein kinase C activation leads to additional protein-protein interactions with functional Fc gamma RIIa.
- These interactions restrict the lateral mobility of Fc gamma RIIa.
- The specific interacting proteins and interaction mechanisms require further investigation.