Confocal, microdomains of fluorescence in RBCs

Dear LIST:

NEED GUIDANCE.	I observe discrete localized microdomains of  
fluorescence in confocal microscopic images of erythrocytes (equine  
RBCs) made permeable (paraformaldehyde) and labeled with annexin V- 
FITC.  Prior to labeling, the RBCs had been heat incubated (37 °C)  
for a duration (12 hrs) that nearly depletes ATP, but the cells were  
still discoid (normal biconcave shape) and not yet transformed into  
echinocytes.   I presume that (by permeabilizing the RBC membrane)  
the fluorescent microdomains are intracellular.

Can anyone tell me if the discrete localized domains might be  
aggregated phosphatidylserine molecules in the membrane inner bilayer  
leaflet?  Or, are they something else?

I would appreciate any help --- with references please.

Thanx,		  John
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John H. Boucher, DVM, PhD
Email:	Jbouch@verizon.net.