Drosophila Futsch/22C10 is a MAP1B-like protein required for dendritic andaxonal development

Here we report the description of the Drosophila gene futsch, which encodes a protein recognized by the monoclonal antibody 22C10 that has been widely used to visualize neuronal morphology and axonal projections. The Futsch p rotein is 5327 amino acids in length. It localizes to the microtubule compa rtment of the cell and associates with microtubules in vitro. The N- and C- terminal domains of Futsch are homologous to the vertebrate MAP1B microtubu le-associated protein. The central domain of the Futsch protein is highly r epetitive and shows sequence similarity to neurofilament proteins of which no Drosophila homologs have been reported. Loss-of-function analyses demons trate that during embryogenesis Futsch is necessary for dendritic and axona l growth. Gain-of-function analyses demonstrate a functional interaction of Futsch with other MAPs. In addition, we show that during development, futs ch expression is negatively regulated in non-neuronal tissues.