Immunological heterogeneity of synaptic and extrasynaptic forms of non-erythroid α-spectrin in the rat retina

Abstract

α-, β- Spectrin is ubiquitously distributed in neuronal compartments, i.e. at the plasma membrane of neuronal cell bodies, axonal and dendritic processes, pre- and postsynaptic nerve terminals and around synaptic vesicles, ‘Brain Res. Bull. 50 (1999) 345’. Ultrastructural analyses in the rat retina using the monoclonal antibody AA6, ‘Hear. Res. 43 (1990) 199, against non-erythroid α-spectrin, αSPII (spectrin nomenclature according to ‘Blood 81 (1993) 3173’), revealed that the antibody intensively labeled the cytoplasmic face of the plasma membrane in virtually all neuronal processes. However, no significant immunolabel was observed at the presynaptic plasma membrane, around synaptic vesicles, at presynaptic densities and synaptic ribbons. Therefore, synaptic non-erythroid α-spectrin differs immunologically from extrasynaptic non-erythroid α-spectrin. This heterogeneity might contribute to the generation of distinct retinal microdomains.