Correlative statistical analysis and computer modelling of intramembraneous particle distributions in human erythrocyte membranes.

The planar distribution of intramembranous particles on the P faces of freeze-fractured human erythrocyte membranes is characterized by radial distribution, angular distribution and differential density distribution analysis. Various degrees of intramembranous particle aggregation induced by spectrin removal and low pH are differentiated through computation. Random hard disk models with various disk diameters are built for comparison studies. In all samples, the 80 +/- 10 A particles are found to have a preferred neighboring distance of 100 +/- 10 A, but no preferred angular relation is found between neighboring particles. A pattern recognition process using both radial and density distribution analyses reveals that none of the particle distributions observed may be regarded as random. The fact that the particle distributions observed are neither even nor random suggests that factors other than long range electrostatic force alone are involved in determining the particle distribution.