Yeast phosphatidylinositol transfer protein (Sec14p) is essential for Golgi secretory function. It is widely accepted, though unproven, that phosphatidylinositol transfer between membranes represents the physiological activity of phosphatidylinositol transfer proteins (PITPs). We report that Sec14pK66,239A is inactivated for phosphatidylinositol, but not phosphatidylcholine (PC), transfer activity. As expected, Sec14pK66,239A fails to meet established criteria for a PITP in vitro and fails to stimulate phosphoinositide production in vivo. However, its expression efficiently rescues the lethality and Golgi secretory defects associated with sec14-1ts and sec14 null mutations. This complementation requires neither phospholipase D activation nor the involvement of a novel class of minor yeast PITPs. These findings indicate that PI binding/transfer is remarkably dispensable for Sec14p function in vivo.

• PMID: 10488334
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Reference Type

Journal Article | Research Support, U.S. Gov't, P.H.S.

Authors

Phillips SE, Sha B, Topalof L, Xie Z, Alb JG, Klenchin VA, Swigart P, Cockcroft S, Martin TF, Luo M, ... Show all

Primary Lit For

SPO14 | SEC14

Additional Lit For

Review For