Figure 3. PFN1 and PFN2a are enriched at postsynaptic sites in the adult rat brain.

(A): Ultrastructural localisation of PFN1 (upper row) and 2a (centre row) in the cortex (left column), CA1 region of the hippocampus (centre column) and cerebellar cortex (right column) as seen with pre-embedding immunogold labelling. Immunogold labelling of synaptophysin (bottom rows), a presynaptic marker, served to demonstrate the localisation of both profilin isoforms in synapses. Sp: dendritic spine. Bars: 50 nm. (B): Quantitation of PFN1 and PFN2a immunoreactivity in pre- and postsynaptic structures in cortex, hippocampus and cerebellum. The Y-axis represents the percentage of pre- and postsynapses positive for gold particles. Note that both isoforms are more densely concentrated in postsynaptic than in presynaptic structures. (25–50 synapses per experiment, mean errors are based on 2 independent experiments; * P<0.05, statistical analysis by paired t-test).