Phosphatidylinositol transfer protein (PITPalpha) stimulates in vitro intra-Golgi transport.

Using a cell-free assay designed to reconstitute cis-to-medial intra-Golgi vesicular transport, we identified at least four crude activities in bovine brain cytosol that stimulate this assay. We have purified one of these activities to near homogeneity and have identified this Mr 36 kDa protein to be the alpha isoform of phosphatidylinositol transfer protein (PITPalpha) by N-terminal peptide sequencing, immunoreactivity with PITP-specific antisera, and the ability of recombinant PITPalpha to stimulate in vitro intra-Golgi transport. From these data, we conclude that in vitro Golgi transport is facilitated by PITPalpha.