Cloning of a novel amphiphysin isoform edna composed of multiple splicing variants and their differential tissue expression

Amphiphysin, an Stt3-domain containing protein concentrated in nerve terminals, is believed to be involved in the synaptic vesicle recycling. We have cloned cDNAs of a novel isoform of amphiphysin from mammals (man, rat, and mouse) by utilizing sequence information for homologous ESTs accumulated in databases. More than 10 subtypes of the isoform with 50-60 amino acid identity to the human amphiphysin were identified by a conventional library screening and PCR amplification of cDNA libraries. Each subtype probably represents a splicing variant of a single gene transcript. Analysis of mRNA expression in various tissues by RT-PCR showed that the isoform is more ubiquitously distributed than the canonical amphiphysin which is almost restricted to the CNS. Expression spectrum of the isoform subtypes, however, is significantly different in several tissues examined, suggesting that they are involved in endocytotic processes that are unique to each cell type.