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PubMed · 8798761

Tissue-specific alternative splicing generates two synaptojanin isoforms with differential membrane binding properties.

A R Ramjaun·P S McPherson
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Abstract

Synaptojanin is an Src homology 3 domain-binding inositol 5-phosphatase that is thought to function in synaptic vesicle endocytosis. It is encoded by a cDNA with two open reading frames separated by an in-frame stop codon. The first open reading frame encodes a 145-kDa form of the protein, whereas a 170-kDa isoform appears to be composed of both open reading frames and contains additional Src homology 3 domain-binding consensus sequences. Here, we demonstrate that the two synaptojanin isoforms are generated by the alternative use of an exon containing the stop codon. Whereas the 145-kDa isoform is highly enriched in adult brain, the 170-kDa isoform is excluded from this tissue and has a widespread distribution in non-neuronal cells. Unlike the 145-kDa isoform, which can be removed from membranes by a low salt wash, the 170-kDa isoform remains membrane-associated, even in the presence of 1 salt. Further, the 170-kDa form, but not the 145-kDa form, can be isolated from membranes as part of a large molecular weight complex. These properties may allow the 170-kDa isoform of synaptojanin to play a unique and perhaps more general role in endocytosis as compared with the 145-kDa isoform.

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Alternative SplicingAmino Acid SequenceBase SequenceBrainCell MembraneDNA, ComplementaryEndocytosisMolecular Sequence DataMolecular WeightNerve Tissue ProteinsPC12 CellsPhosphoric Monoester HydrolasesPolymerase Chain ReactionProtein Bindingsrc Homology DomainsJournal ArticleResearch Support, Non-U.S. Gov't

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A R Ramjaun, P S McPherson. 1996-10-04. Tissue-specific alternative splicing generates two synaptojanin isoforms with differential membrane binding properties.. https://doi.org/10.1074/jbc.271.40.24856

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