Skinner HB, et al. (1995) The Saccharomyces cerevisiae phosphatidylinositol-transfer protein effects a ligand-dependent inhibition of choline-phosphate cytidylyltransferase activity. Proc Natl Acad Sci U S A 92(1):112-6
Abstract: The Saccharomyces cerevisiae protein SEC14p is required for Golgi function and cell viability in vivo. This requirement is obviated by mutations that specifically inactivate the CDP-choline pathway for phosphatidylcholine biosynthesis. The biochemical basis for the in vivo relationship between SEC14p function and the CDP-choline pathway has remained obscure. We now report that SEC14p effects an in vivo depression of CDP-choline pathway activity by inhibiting choline-phosphate cytidylyltransferase (CCTase; EC 22.214.171.124), the rate-determining enzyme of the CDP-choline pathway. Moreover, this SEC14p-mediated inhibition of CCTase was recapitulated in vitro and was saturable. Finally, whereas the SEC14p-dependent inhibition of CCTase in vitro was markedly reduced under assay conditions that were expected to increase levels of phosphatidylinositol-bound SEC14p, assay conditions expected to increase levels of phosphatidylcholine-bound SEC14p resulted in significant potentiation of CCTase inhibition. The collective data suggest that the phosphatidylcholine-bound form of SEC14p effects an essential repression of CDP-choline pathway activity in Golgi membranes by inhibiting CCTase and that the phospholipid-binding/exchange activity of SEC14p represents a mechanism by which the regulatory activity of SEC14p is itself controlled.
|Status: Published||Type: Journal Article||PubMed ID: 7816798|
Topics addressed in this paper
Number of different genes curated to this paper: 2
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