The patterns of expression of two ankyrin isoforms demonstrate distinct steps in the assembly of the membrane skeleton in neuronal morphogenesis.

We have identified in chicken neurons two membrane-bound isoforms of goblin (ankyrin), the specific membrane attachment protein for spectrin in avian erythrocytes, which exhibit distinct patterns of expression and assembly during neuronal morphogenesis. Early in cerebellar and retinal development, neither goblin isoform is detected in mitotic cells. Subsequently, beta-goblin (Mr 237,000) is expressed in postmitotic cells, and gradually accumulates with alpha gamma (brain) spectrin on the neuronal plasma membrane during the phase of cell growth. At the onset of synaptogenesis and the cessation of cell growth, their levels of synthesis decline sharply while the assembled proteins remain as stable membrane components. Concomitantly, there is a dramatic induction in the accumulation of alpha-goblin (erythroid goblin; Mr 260,000) and alpha beta (erythroid) spectrin, whose assembly is limited to the plasma membrane of perikarya and dendrites.